code: def nside_to_level(nside):
      
      nside = np.asarray(nside, dtype=np.int64)
  
      _validate_nside(nside)
      return np.log2(nside).astype(np.int64)
docs: Find the HEALPix level for a given nside.
  
      This is given by ``level = log2(nside)``.
  
      This function is the inverse of `level_to_nside`.
  
      Parameters
      ----------
      nside : int
          The number of pixels on the side of one of the 12 'top-level' HEALPix tiles.
          Must be a power of two.
  
      Returns
      -------
      level : int
          The level of the HEALPix cells