'Test for sufficient PUT responses from backend nodes to proceed with
PUT handling.
:param statuses: a list of response statuses.
:param num_nodes: number of backend nodes to which PUT requests may be
issued.
:param min_responses: (optional) minimum number of nodes required to
have responded with satisfactory status code.
:return: True if sufficient backend responses have returned a
satisfactory status code.'

def _have_adequate_put_responses(self, statuses, num_nodes, min_responses):

    raise NotImplementedError
