class_docstr: Class that creates a callable object that uses mouse clicks or key
  clicks on a figure window to place contour labels.
docstr: This will be called if an event involving a button other than
  2 or 3 occcurs.  This will add a label to a contour.
docstr_tok: ["This","will","be","called","if","an","event","involving","a","button","other","than","2","or","3","occcurs",".","This","will","add","a","label","to","a","contour","."]
code: def button1(self, event):
      """
      This will be called if an event involving a button other than
      2 or 3 occcurs.  This will add a label to a contour.
      """
  
      # Shorthand
      if event.inaxes == self.cs.ax:
          self.cs.add_label_near(
              event.x,
              event.y,
              self.inline,
              inline_spacing=self.inline_spacing,
              transform=False,
          )
          self.fig.canvas.draw()
      else:  # Remove event if not valid
          BlockingInput.pop(self)
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import six
  import matplotlib.lines
  import logging
label_desc: Use image node_id 4 for calling the BlockingContourLabeler obj's underlying member method code with example usage: obj.button1(event) without return types