class_docstr: Class that creates a callable object to retrieve events in a
  blocking way.
code: def __init__(self, fig, eventslist=()):
      self.fig = fig
      self.eventslist = eventslist
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import six
  import matplotlib.lines
  import logging
label_desc: Use image node_id 1 to create a new BlockingInput object from inherited base classes: object with example: obj = BlockingInput(fig, eventslist)