code: def predict_type(self):
          
          inst_type = self.inst_ref.predict_type()
  
          if self.prop_ref_type.allowed_inst_type != inst_type:
              self.msg.fatal(
                  "'%s' is not a valid property of instance" % self.prop_ref_type.get_name(),
                  self.src_ref
              )
  
          return self.prop_ref_type
docs: Predict the type of the inst_ref, and make sure the property being
          referenced is allowed