code: def zeros(dur=None):
    
    if dur is None or (isinf(dur) and dur > 0):
      while True:
        yield 0.0
    for x in xrange(int(.5 + dur)):
      yield 0.0
docs: Zeros/zeroes stream generator.
    You may sum your endless stream by this to enforce an end to it.
  
    Parameters
    ----------
    dur :
      Duration, in number of samples; endless if not given.
  
    Returns
    -------
    Stream that repeats "0.0" during a given time duration (if any) or
    endlessly.