class_docstr: Class that creates a callable object to retrieve mouse clicks in a
  blocking way.
  
  This class will also retrieve keyboard clicks and treat them like
  appropriate mouse clicks (delete and backspace are like mouse button 3,
  enter is like mouse button 2 and all others are like mouse button 1).
docstr: This add the coordinates of an event to the list of clicks
docstr_tok: ["This","add","the","coordinates","of","an","event","to","the","list","of","clicks"]
code: def add_click(self, event):
      """
      This add the coordinates of an event to the list of clicks
      """
      self.clicks.append((event.xdata, event.ydata))
      _log.info(
          "input %i: %f,%f"
          % (len(self.clicks), event.xdata, event.ydata)
      )
  
      # If desired plot up click
      if self.show_clicks:
          line = mlines.Line2D(
              [event.xdata], [event.ydata], marker="+", color="r"
          )
          event.inaxes.add_line(line)
          self.marks.append(line)
          self.fig.canvas.draw()
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import six
  import matplotlib.lines
  import logging
label_desc: Use image node_id 8 for calling the BlockingMouseInput obj's underlying member method code with example usage: obj.add_click(event) without return types