class_docstr: Abstract class for generating neighbors.
  
  This class is to be inherited by the class that actually implements the method
  to generate neighbors.
code: def __init__(self):
      raise NotImplementedError
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
label_desc: Use image node_id 1 to create a new GenNeighbor object from inherited base classes: object with example: obj = GenNeighbor()