'Ensure that all properties identified as required by the schema are
set.'

def VerifyHasRequiredProperties(self):

    for (property, attributes) in self._schema.iteritems():
        (is_list, property_type, is_strong, is_required) = attributes[0:4]
        if (is_required and (not (property in self._properties))):
            raise KeyError(((self.__class__.__name__ + '    requires    ') + property))
