docs: def raises(self, exc):
          """Set last call to raise an exception class or instance.
  
          For example::
  
              >>> import fudge
              >>> db = fudge.Fake('db').provides('insert').raises(ValueError("not enough parameters for insert"))
              >>> db.insert()
              Traceback (most recent call last):
              ...
              ValueError: not enough parameters for insert
  
          """
          exp = self._get_current_call()
          exp.exception_to_raise = exc
          return self