add example (google#2)

Author: johnsonmh

CHANGELOG.md

@@ -0,0 +1,3 @@
+## [0.1.0] - 2020-04-24
+
+Initial release. 

example/main.dart

@@ -0,0 +1,17 @@
+
+import 'package:basics/basics.dart';
+
+main() async {
+  const numbers = <int>[2, 4, 8];
+
+  if (numbers.isNotNull && numbers.all((n) => n.isEven)) {
+    print('All numbers are even.');
+  }
+
+  print('sum of numbers is: ${numbers.sum()}');
+
+  for (var i in 5.range) {
+    print('waiting 500 milliseconds...');
+    await Future.delayed(500.milliseconds);
+  }
+}

pubspec.yaml

@@ -7,7 +7,7 @@ authors:
   - garciaz@google.com <garciaz@google.com>
 
 environment:
-  sdk: ">=2.7.0 <2.9.0"
+  sdk: ">=2.7.0 <3.0.0"
 dependencies:
   quiver: ^2.1.2+1
 dev_dependencies: