code: def zpad(x, pd, ax):
      
  
      xpd = ((0, 0),)*ax + (pd,) + ((0, 0),)*(x.ndim-ax-1)
      return np.pad(x, xpd, 'constant')
docs: Zero-pad array `x` with `pd = (leading, trailing)` zeros on axis `ax`.
  
      Parameters
      ----------
      x : array_like
        Array to be padded
      pd : tuple
        Sequence of two ints (leading,trailing) specifying number of zeros
        for padding
      ax : int
        Axis to be padded
  
      Returns
      -------
      xp : array_like
        Padded array