'Find out the local name of an attribute
:param attr: An saml.Attribute instance
:return: The local attribute name or "" if no mapping could be made'

def from_format(self, attr):

    if attr.name_format:
        if (self.name_format == attr.name_format):
            try:
                return self._fro[attr.name.lower()]
            except KeyError:
                pass
    else:
        try:
            return self._fro[attr.name.lower()]
        except KeyError:
            pass
    return ''
