text: #------------------------------------------------------------------------------
  #  Copyright (c) 2012, Enthought, Inc.
  #  All rights reserved.
  #------------------------------------------------------------------------------
  from abc import ABCMeta
  
  
  class ABConstrainable(object):
      """ An abstract base class for objects that can be laid out using
      layout helpers.
  
      Minimally, instances need to have `top`, `bottom`, `left`, `right`,
      `width`, `height`, `v_center` and `h_center` attributes which are
      `LinearSymbolic` instances.
  
      """
      __metaclass__ = ABCMeta
  
  