code: def rndmask(shp, frc, dtype=None):
      r
  
      msk = np.asarray(np.random.uniform(-1.0, 1.0, shp), dtype=dtype)
      msk[np.abs(msk) > frc] = 1.0
      msk[np.abs(msk) < frc] = 0.0
      return msk
docs: r"""Return random mask image with values in :math:`\{0,1\}`.
  
      Parameters
      ----------
      s : tuple
        Mask array shape
      frc : float
        Desired fraction of zero pixels
      dtype : data-type or None, optional (default None)
        Data type of mask array
  
      Returns
      -------
      msk : ndarray
        Mask image