'Execute an extension factory.
Loads an extension.  The \'ext_factory\' is the name of a
callable that will be imported and called with one
argument--the extension manager.  The factory callable is
expected to call the register() method at least once.'

def load_extension(self, ext_factory):

    LOG.debug('Loading    extension    %s', ext_factory)
    if isinstance(ext_factory, six.string_types):
        factory = importutils.import_class(ext_factory)
    else:
        factory = ext_factory
    LOG.debug('Calling    extension    factory    %s', ext_factory)
    factory(self)
