def GetSOAPEnvUri(self, version):
        """Return the appropriate SOAP envelope uri for a given
           human-friendly SOAP version string (e.g. '1.1')."""
        attrname = 'NS_SOAP_ENV_%s' % join(split(version, '.'), '_')
        value = getattr(self, attrname, None)
        if value is not None:
            return value
        raise ValueError(
            'Unsupported SOAP version: %s' % version
            )