def name_for_scalar_relationship(base, local_cls, referred_cls, constraint):
    """Return the attribute name that should be used to refer from one
    class to another, for a scalar object reference.

    The default implementation is::

        return referred_cls.__name__.lower()

    Alternate implementations can be specified using the
    :paramref:`.AutomapBase.prepare.name_for_scalar_relationship`
    parameter.

    :param base: the :class:`.AutomapBase` class doing the prepare.

    :param local_cls: the class to be mapped on the local side.

    :param referred_cls: the class to be mapped on the referring side.

    :param constraint: the :class:`.ForeignKeyConstraint` that is being
     inspected to produce this relationship.

    """
    return referred_cls.__name__.lower()