new_contents: from __future__ import absolute_import, print_function, unicode_literals
  from builtins import dict, str
  from indra.statements import *
  from indra.belief import BeliefEngine
  
  ev1 = Evidence(source_api='reach')
  ev2 = Evidence(source_api='trips')
  ev3 = Evidence(source_api='assertion')
  
  
  def test_prior_prob_one():
      be = BeliefEngine()
      prob = 1 - (be.prior_probs['rand']['reach'] +
                  be.prior_probs['syst']['reach'])
      st = Phosphorylation(None, Agent('a'), evidence=[ev1])
      assert(st.belief == 1)
      be.set_prior_probs([st])
      assert(st.belief == prob)
  
  
  def test_prior_prob_two_same():
      be = BeliefEngine()
      prob = 1 - (be.prior_probs['rand']['reach']**2 +
                  be.prior_probs['syst']['reach'])
      st = Phosphorylation(None, Agent('a'), evidence=[ev1, ev1])
      assert(st.belief == 1)
      be.set_prior_probs([st])
      assert(st.belief == prob)
  
  
  def test_prior_prob_two_different():
      be = BeliefEngine()
      prob = 1 - (be.prior_probs['rand']['reach'] +
                   be.prior_probs['syst']['reach']) * \
                 (be.prior_probs['rand']['trips'] +
                   be.prior_probs['syst']['trips'])
      st = Phosphorylation(None, Agent('a'), evidence=[ev1, ev2])
      assert(st.belief == 1)
      be.set_prior_probs([st])
      assert(st.belief == prob)
  
  
  def test_prior_prob_one_two():
      be = BeliefEngine()
      prob = 1 - (be.prior_probs['rand']['reach']**2 +
                   be.prior_probs['syst']['reach']) * \
                 (be.prior_probs['rand']['trips'] +
                   be.prior_probs['syst']['trips'])
      st = Phosphorylation(None, Agent('a'), evidence=[ev1, ev1, ev2])
      assert(st.belief == 1)
      be.set_prior_probs([st])
      assert(st.belief == prob)
  
  
  def test_prior_prob_assertion():
      be = BeliefEngine()
      st = Phosphorylation(None, Agent('a'), evidence=[ev1, ev1, ev2, ev3])
      assert(st.belief == 1)
      be.set_prior_probs([st])
      assert(st.belief == 1)
  
  '''
  def test_hierarchy_probs1():
      be = BeliefEngine()
      st1 = Phosphorylation(None, Agent('a'), evidence=[ev1])
      st2 = Phosphorylation(None, Agent('a'), evidence=[ev2], supports=[st1])
      assert(st.belief == 1)
      be.set_prior_probs([st])
      assert(st.belief == 1)
  '''
  
subject: Add first round of tests