'Validates that the client may request access to the realm.
:param client_key: The client/consumer key.
:param realms: The list of realms that client is requesting access to.
:param request: An oauthlib.common.Request object.
:returns: True or False
This method is invoked when obtaining a request token and should
tie a realm to the request token and after user authorization
this realm restriction should transfer to the access token.
This method is used by
* RequestTokenEndpoint'

def validate_requested_realms(self, client_key, realms, request):

    raise NotImplementedError(u'Subclasses    must    implement    this    function.')
