text: explanations = {
    'gamma': '''
      Proportion of tree modifications that should use mutrel-informed choice for
      node to move, rather than uniform choice
    ''',
  
    'zeta': '''
      Proportion of tree modifications that should use mutrel-informed choice for
      destination to move node to, rather than uniform choice
    ''',
  
    'iota': '''
      Probability of initializing with mutrel-informed tree rather than fully
      branching tree when beginning chain
    '''
  }
  
  defaults = {
    'gamma': 0.7,
    'zeta': 0.7,
    'iota': 0.7,
  }
  
  assert set(explanations.keys()) == set(defaults.keys())
  