code: def _compose_pair(self, role, base):
          '''
          composes onto base by applying the role
          '''
          # apply transformations in role to base
          for attrname in dir(role):
              transformation = getattr(role, attrname)
              self._apply_transformation(role, base, transformation, attrname)
  
          return basf _compose_pair(self, role, base):
          '''
          composes onto base by applying the role
          '''
          # apply transformations in role to base
          for attrname in dir(role):
              transformation = getattr(role, attrname)
              self._apply_transformation(role, base, transformation, attrname)
  
          return base
docs: composes onto base by applying the role