Removed type annotation. Python2 doesn't support it, unfortunately.

Author: jonathanslenders

prompt_toolkit/widgets/base.py

@@ -626,7 +626,7 @@ def _(event):
  dont_extend_height=True)
 
  def _get_text_fragments(self):
- def mouse_handler(mouse_event: MouseEvent):
+ def mouse_handler(mouse_event):
  """
  Set `_selected_index` and `current_value` according to the y
  position of the mouse click event.