Returns `True` if the user identifies with the specified role.

        :param role: A role name or `Role` instance

def has_role(self, role):
        """Returns `True` if the user identifies with the specified role.

        :param role: A role name or `Role` instance"""
        if isinstance(role, string_types):
            return role in (role.name for role in self.roles)
        else:
            return role in self.roles