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‎all/index.html

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@@ -43,107 +43,108 @@ <h1><strong style="font-size:35">$sam_frances</strong>->web_development($program
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<aside id="featured">
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<article>
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<h2 class="blog_post_heading"><a href="https://samfrances.co.uk/posts/2018/May/28/now-9/">What I'm doing now</a></h2>
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<h2 class="blog_post_heading"><a href="https://samfrances.co.uk/posts/2018/Jun/28/using-generators-to-build-async-agnostic-api-clients/">Using generators to build async agnostic API clients</a></h2>
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<footer class="blog_post_dateline">
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<span>Mon 28 May 2018</span>
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</footer><!-- /.post-info --><p><em>(This is my <a href="http://nownownow.com/about">now page</a>. It tells you what I'm doing at the moment. It also reminds <strong>me</strong> what I have decided I want to be doing at the moment.)</em></p>
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<p>Reading:</p>
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<ul>
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<li><del><a href="https://pragprog.com/book/cdc-elixir/learn-functional-programming-with-elixir">Learn Functional Programming with Elixir</a>
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by Ulisses Almeida</del> (finished)</li>
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<li>&#43; <a href="http://shop.oreilly.com/product/0636920030584.do">Introducing Elixir</a> by Simon St. Laurent and J. Eisenberg</li>
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<li>&#43; <a href="http://www.obeythetestinggoat.com/">Test-Driven Development with Python, 2nd Edition</a> by Harry J.W. Percival</li>
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<li><del><a href="http://shop.oreilly.com/product/0636920032502.do">Lightweight Django</a> by Julia Elman and Mark Lavin</del> (finished)</li>
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</ul>
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<p>Looking forward to reading:</p>
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<ul>
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<li><a href="https://www.manning.com/books/amazon-web-services-in-action">Amazon Web Services in Action</a> by Michael Wittig &amp;
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Andreas Wittig</li>
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<li><a href="https://leanpub.com/javascriptallongesix">JavaScript Allongé, the "Six" Edition</a></li>
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<li><a href="https://bleedingedgepress.com/developing-a-redux-edge/">Developing a Redux Edge</a> by Johannes Lumpe, Karl Purkhardt,
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Art Muller, Darío Cravero &amp; Ezekiel Chentnik</li>
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<li><a href="https://www.manning.com/books/docker-in-action">Docker in Action</a> by Jeff Nickoloff</li>
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<li><a href="https://www.manning.com/books/rabbitmq-in-depth">RabbitMQ in Depth</a> by Gavin M. Roy</li>
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<li><a href="https://www.nostarch.com/howlinuxworks2">How Linux Works</a> by Brian Ward</li>
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<li><a href="http://www.apress.com/la/book/9781430258544">Foundations of Python Network Programming</a> by Brandon Rhodes</li>
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<li><a href="http://zguide.zeromq.org/page:all">ZeroMQ</a> by Pieter Hintjens</li>
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<li><a href="https://www.ansiblefordevops.com/">Ansible for DevOps</a> by Jeff Geerling</li>
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<li><a href="http://haskellbook.com/">Haskell programming from first principles</a> by Christopher Allen and Julie Moronuki</li>
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<li><a href="https://www.amazon.co.uk/Foundation-Mathematics-K-Stroud/dp/0230579078/">Foundation Mathematics</a> by K.A. Stroud</li>
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<li><a href="http://www.headfirstlabs.com/books/hfalg/">Head First Algebra</a> by Tracy Pilone &amp; Dan Pilone</li>
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<li><a href="http://www.librarything.com/catalog.php?view=samfrances&amp;collection=-1&amp;shelf=list&amp;sort=dateread">So many books!!!</a></li>
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</ul>
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<p>Studying:</p>
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<ul>
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<li><a href="https://www.edx.org/micromasters/software-development">UBCx: Software Development MicroMasters</a> on <a href="https://www.edx.org">Edx</a></li>
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</ul>
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<p>Working on:</p>
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<ul>
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<li>Lots of interesting stuff for <a href="https://cydarmedical.com/">Cydar</a>, involving things like Django Rest Framework, Celery, Ansible, and AWS</li>
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</ul> </article>
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<span>Thu 28 June 2018</span>
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<span>| tags: <a href="https://samfrances.co.uk/tag/python.html">python</a>, <a href="https://samfrances.co.uk/tag/asyncio.html">asyncio</a>, <a href="https://samfrances.co.uk/tag/async.html">async</a></span>
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</footer><!-- /.post-info --><p>I'm a big fan of asyncio, couroutines and <code>async</code>/<code>await</code> syntax in
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Python 3.5+. However, they come with some well documented downsides. Not least
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among these is the
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<a href="http://journal.stuffwithstuff.com/2015/02/01/what-color-is-your-function/">red/blue function problem</a>.
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Coroutines can call plain functions, but only a coroutine can await another
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coroutine (unless you count running it by directly invoking the event loop).
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Meanwhile, if a coroutine calls a plain function which triggers some sort of
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blocking IO, the whole event loop is blocked.</p>
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<p>I have found the red/blue divide particularly annoying in the context of web
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API clients. Take <a href="https://boto3.readthedocs.io/">boto3</a>, the popular client for
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AWS's various APIs. This only works in a synchronous context. Another project,
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<a href="https://github.com/aio-libs/aiobotocore">aiobotocore</a>, provides some of these
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capabilities in an async context, but doesn't support all services and operations.</p>
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<p>Yet, many of the things API clients do have nothing directly to do with IO,
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async or otherwise. Preparing a HTTP request - determining what headers to
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use, constructing a request body, calculating signatures and other
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authentication details - is a purely functional, IO-free business.
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The same goes for interpreting a HTTP response.</p>
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<p>A function or method in an API client is like a sandwich where constructing
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the request and interpreting the response are the two pieces of bread, and sending
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the request is the filling. We ought to be able to use the same bread for any
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type of sandwich, without caring if the filling is ham, cheese, or something else.</p>
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<p>Ok, enough with the shaky metaphors. Time for some code.</p>
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<p>The strategy I have stumbled upon is to write the pure
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request-construction / response-interpretation logic as a generator function,
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which yields in the middle. The generator yields an object providing details of
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the HTTP request it wishes to be sent, ceding control to "something else, I care not
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what" which executes the actual web request, and sends an object representing the response
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back into the generator. The generator then processes the response.</p>
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<p>Here's a toy API client for <a href="http://www.icndb.com/">The Internet Chuck Norris Database</a>.</p>
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<script src="https://gitlab.com/samfrances/async-agnostic-api-client-example/snippets/1729032.js"></script>
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<p>I still haven't decided if this is a good strategy overall, although it
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certainly seems to achieve its immediate goal of allowing a large chunk of
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code to be shared between sync and async clients. Comments welcome.</p>
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<p>¡Hasta pronto!</p> </article>
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</aside><!-- /#featured -->
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<section id="other_articles">
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<h2>Other articles</h2>
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<ol id="posts-list" class="hfeed">
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<h2 class="blog_post_heading"><a href="https://samfrances.co.uk/posts/2018/Mar/28/now-8/" rel="bookmark"
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<h2 class="blog_post_heading"><a href="https://samfrances.co.uk/posts/2018/May/28/now-9/" rel="bookmark"
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title="Permalink to What I'm doing now">What I'm doing now</a></h2>
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</header>
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<div class="entry-content">
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<footer class="blog_post_dateline">
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<span>Wed 28 March 2018</span>
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<span>Mon 28 May 2018</span>
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</footer><!-- /.post-info --> <p>What I'm doing now</p>
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<p><a class="readmore" href="https://samfrances.co.uk/posts/2018/Mar/28/now-8/">read more</a></p>
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<p><a class="readmore" href="https://samfrances.co.uk/posts/2018/May/28/now-9/">read more</a></p>
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<h2 class="blog_post_heading"><a href="https://samfrances.co.uk/posts/2017/Dec/11/now-7/" rel="bookmark"
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<h2 class="blog_post_heading"><a href="https://samfrances.co.uk/posts/2018/Mar/28/now-8/" rel="bookmark"
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title="Permalink to What I'm doing now">What I'm doing now</a></h2>
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<span>Mon 11 December 2017</span>
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<span>Wed 28 March 2018</span>
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</footer><!-- /.post-info --> <p>What I'm doing now</p>
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<p><a class="readmore" href="https://samfrances.co.uk/posts/2017/Dec/11/now-7/">read more</a></p>
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<p><a class="readmore" href="https://samfrances.co.uk/posts/2018/Mar/28/now-8/">read more</a></p>
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</div><!-- /.entry-content -->
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<h2 class="blog_post_heading"><a href="https://samfrances.co.uk/posts/2017/Nov/19/now-6/" rel="bookmark"
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<h2 class="blog_post_heading"><a href="https://samfrances.co.uk/posts/2017/Dec/11/now-7/" rel="bookmark"
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<span>Sun 19 November 2017</span>
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<span>Mon 11 December 2017</span>
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</footer><!-- /.post-info --> <p>What I'm doing now</p>
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<p><a class="readmore" href="https://samfrances.co.uk/posts/2017/Nov/19/now-6/">read more</a></p>
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<p><a class="readmore" href="https://samfrances.co.uk/posts/2017/Dec/11/now-7/">read more</a></p>
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<h2 class="blog_post_heading"><a href="https://samfrances.co.uk/posts/2017/Apr/24/now-5/" rel="bookmark"
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<h2 class="blog_post_heading"><a href="https://samfrances.co.uk/posts/2017/Nov/19/now-6/" rel="bookmark"
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title="Permalink to What I'm doing now">What I'm doing now</a></h2>
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<span>Mon 24 April 2017</span>
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<span>Sun 19 November 2017</span>
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</footer><!-- /.post-info --> <p>What I'm doing now</p>
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<p><a class="readmore" href="https://samfrances.co.uk/posts/2017/Apr/24/now-5/">read more</a></p>
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<p><a class="readmore" href="https://samfrances.co.uk/posts/2017/Nov/19/now-6/">read more</a></p>
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</div><!-- /.entry-content -->
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</article></li>
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<h3>Tags</h3>
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<p>
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<a href="https://samfrances.co.uk/tag/node.html">node</a>, <a href="https://samfrances.co.uk/tag/pelican.html">pelican</a>, <a href="https://samfrances.co.uk/tag/canvas.html">canvas</a>, <a href="https://samfrances.co.uk/tag/design-patterns.html">design-patterns</a>, <a href="https://samfrances.co.uk/tag/python.html">python</a>, <a href="https://samfrances.co.uk/tag/javascript.html">javascript</a>, <a href="https://samfrances.co.uk/tag/aws.html">aws</a>, <a href="https://samfrances.co.uk/tag/django.html">django</a>, <a href="https://samfrances.co.uk/tag/ansible.html">ansible</a>, <a href="https://samfrances.co.uk/tag/html5.html">html5</a>, <a href="https://samfrances.co.uk/tag/tutorials.html">tutorials</a> </p>
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<a href="https://samfrances.co.uk/tag/node.html">node</a>, <a href="https://samfrances.co.uk/tag/pelican.html">pelican</a>, <a href="https://samfrances.co.uk/tag/canvas.html">canvas</a>, <a href="https://samfrances.co.uk/tag/design-patterns.html">design-patterns</a>, <a href="https://samfrances.co.uk/tag/python.html">python</a>, <a href="https://samfrances.co.uk/tag/javascript.html">javascript</a>, <a href="https://samfrances.co.uk/tag/aws.html">aws</a>, <a href="https://samfrances.co.uk/tag/django.html">django</a>, <a href="https://samfrances.co.uk/tag/ansible.html">ansible</a>, <a href="https://samfrances.co.uk/tag/html5.html">html5</a>, <a href="https://samfrances.co.uk/tag/tutorials.html">tutorials</a>, <a href="https://samfrances.co.uk/tag/async.html">async</a>, <a href="https://samfrances.co.uk/tag/asyncio.html">asyncio</a> </p>
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<h3>Feeds</h3>
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‎all/index2.html

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<h2 class="blog_post_heading"><a href="https://samfrances.co.uk/posts/2017/Apr/24/now-5/" rel="bookmark"
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title="Permalink to What I'm doing now">What I'm doing now</a></h2>
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</header>
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<div class="entry-content">
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<footer class="blog_post_dateline">
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<span>Mon 24 April 2017</span>
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</footer><!-- /.post-info --> <p>What I'm doing now</p>
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<p><a class="readmore" href="https://samfrances.co.uk/posts/2017/Apr/24/now-5/">read more</a></p>
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</div><!-- /.entry-content -->
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</article></li>
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<p><a class="readmore" href="https://samfrances.co.uk/posts/2017/Jan/30/now-1/">read more</a></p>
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<h2 class="blog_post_heading"><a href="https://samfrances.co.uk/posts/2017/Jan/28/now-0/" rel="bookmark"
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title="Permalink to What I'm doing now">What I'm doing now</a></h2>
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</header>
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<footer class="blog_post_dateline">
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<span>Sat 28 January 2017</span>
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<p><a class="readmore" href="https://samfrances.co.uk/posts/2017/Jan/28/now-0/">read more</a></p>
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<a href="https://samfrances.co.uk/all/index.html">&laquo;</a>
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<h3>Tags</h3>
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<p>
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<a href="https://samfrances.co.uk/tag/node.html">node</a>, <a href="https://samfrances.co.uk/tag/pelican.html">pelican</a>, <a href="https://samfrances.co.uk/tag/canvas.html">canvas</a>, <a href="https://samfrances.co.uk/tag/design-patterns.html">design-patterns</a>, <a href="https://samfrances.co.uk/tag/python.html">python</a>, <a href="https://samfrances.co.uk/tag/javascript.html">javascript</a>, <a href="https://samfrances.co.uk/tag/aws.html">aws</a>, <a href="https://samfrances.co.uk/tag/django.html">django</a>, <a href="https://samfrances.co.uk/tag/ansible.html">ansible</a>, <a href="https://samfrances.co.uk/tag/html5.html">html5</a>, <a href="https://samfrances.co.uk/tag/tutorials.html">tutorials</a> </p>
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<a href="https://samfrances.co.uk/tag/node.html">node</a>, <a href="https://samfrances.co.uk/tag/pelican.html">pelican</a>, <a href="https://samfrances.co.uk/tag/canvas.html">canvas</a>, <a href="https://samfrances.co.uk/tag/design-patterns.html">design-patterns</a>, <a href="https://samfrances.co.uk/tag/python.html">python</a>, <a href="https://samfrances.co.uk/tag/javascript.html">javascript</a>, <a href="https://samfrances.co.uk/tag/aws.html">aws</a>, <a href="https://samfrances.co.uk/tag/django.html">django</a>, <a href="https://samfrances.co.uk/tag/ansible.html">ansible</a>, <a href="https://samfrances.co.uk/tag/html5.html">html5</a>, <a href="https://samfrances.co.uk/tag/tutorials.html">tutorials</a>, <a href="https://samfrances.co.uk/tag/async.html">async</a>, <a href="https://samfrances.co.uk/tag/asyncio.html">asyncio</a> </p>
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