class_docstr: Class that creates a callable object to retrieve events in a
  blocking way.
code: def pop(self, index=-1):
      self.pop_event(index)
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import six
  import matplotlib.lines
  import logging
label_desc: Use image node_id 7 for calling the BlockingInput obj's underlying member method code with example usage: obj.pop(index) without return types