'Gets the pending message count
Keyword Arguments:
partitions (list): list of partitions to check for, default is to check all'

def pending(self, partitions=None):

    if (partitions is None):
        partitions = self.offsets.keys()
    total = 0
    reqs = []
    for partition in partitions:
        reqs.append(OffsetRequestPayload(self.topic, partition, (-1), 1))
    resps = self.client.send_offset_request(reqs)
    for resp in resps:
        partition = resp.partition
        pending = resp.offsets[0]
        offset = self.offsets[partition]
        total += (pending - offset)
    return total
