Add examples of prompt_toolkit

cli/foo.py

@@ -0,0 +1,27 @@
+from prompt_toolkit import PromptSession
+from prompt_toolkit.completion import Completer, Completion
+
+
+class Completer(Completer):
+    def get_completions(self, document, complete_event):
+        yield Completion('foo', start_position=0, style='bg:ansiyellow fg:ansiblack')
+        yield Completion('bar', start_position=0, style='underline')
+
+class Foo:
+    def __init__(self):
+        self.session = PromptSession()
+
+    def run(self):
+        print(self.multi_line_prompt())
+
+
+    def multi_line_prompt(self):
+        """ Prompt the user for input, allowing multiple lines with default text. """
+        return self.session.prompt('Give me some input: ', multiline=True, default='Hello\nWorld\n', completer=Completer())
+
+def main():
+    foo = Foo()
+    foo.run()
+
+if __name__ == '__main__':
+    main()