text: """
  Distributions illustrating three types of dependency among two variables.
  """
  
  from __future__ import division
  
  from .. import Distribution
  
  __all__ = ['stacked', 'mixed']
  
  
  # the first four outcomes are conditional dependence
  # the next two are conditional independence
  # the last four are intrinsic dependence
  _stacked_outcomes = [
      '000',
      '011',
      '101',
      '110',
      '222',
      '333',
      '444',
      '445',
      '554',
      '555',
  ]
  _stacked_pmf = [1/12]*4 + [1/6]*2 + [1/12]*4
  stacked = Distribution(_stacked_outcomes, _stacked_pmf)
  
  
  # each var expands in binary as:
  #    (conditional dependence, conditional independence, intrinsic dependence)
  _mixed_outcomes = [
      '000',
      '044',
      '404',
      '440',
      '222',
      '266',
      '626',
      '662',
      '110',
      '154',
      '514',
      '550',
      '332',
      '376',
      '736',
      '772',
      '001',
      '045',
      '405',
      '441',
      '223',
      '267',
      '627',
      '663',
      '111',
      '155',
      '515',
      '551',
      '333',
      '377',
      '737',
      '773',
  ]
  _mixed_pmf = [1/32]*32
  mixed = Distribution(_mixed_outcomes, _mixed_pmf)
  