John

's comments, other minor edits

Author: Atma Mani

guide/15-working-with-geometries/part1_introduction_what_is_geometry.ipynb

@@ -4,7 +4,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "# Introduction - what is geometry?"
+    "# Part 1: Introduction - what is geometry?"
    ]
   },
   {

guide/15-working-with-geometries/part2_working_with_geometries.ipynb

@@ -4,7 +4,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "# Working with Geometries"
+    "# Part 2:  Working with Geometries"
    ]
   },
   {
@@ -23,7 +23,7 @@
    "source": [
     "## Creating geometries\n",
     "\n",
-    "The `arcgis.geometry` module defines geometry types for working with geographic features in a GIS. It provides functions which use geometric types as input and output as well as functions for easily converting geometries between different representations.\n",
+    "The [`arcgis.geometry`](https://developers.arcgis.com/python/api-reference/arcgis.geometry.html#) module defines geometry types for working with geographic features in a GIS. It provides functions which use geometric types as input and output as well as functions for easily converting geometries between different representations.\n",
     "\n",
     "Several functions in this module accept geometries represented as Python dictionary objects. To get started, we import the following classes and functions from the `geometry` module."
    ]
@@ -287,6 +287,13 @@
     "print(polyline.is_valid())"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The geometry we just created is invalid, yet the API allowed you to still create it. This because, the API does not check for validity in an eager fashion. Rather it checks when `is_valid()` is called, in an on-demand fashion. This is for performance reasons."
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 49,