'Args:
cnt: how many towers to feed to.'

def next_feed(self, cnt=1):

    cnt = int(cnt)
    assert (cnt < self._nr_tower)
    feed = {}
    for t in range(cnt):
        dp = next(self._cb._itr)
        f = dict(zip(self._placehdrs_per_tower[t], dp))
        feed.update(f)
    return feed
