code: def _fmt_res(fmt, max_res=False):
      
      if isinstance(fmt, list):
          if max_res:
              # Allow None
              bit_res = np.max([_fmt_res(f) for f in fmt if f is not None])
          else:
              bit_res = [_fmt_res(f) for f in fmt]
          return bit_res
  
      return BIT_RES[fmt]
docs: Return the resolution of the WFDB dat format(s). Uses the BIT_RES
      dictionary, but accepts lists and other options.
  
      Parameters
      ----------
      fmt : str
          The wfdb format. Can be a list of valid fmts. If it is a list,
          and `max_res` is True, the list may contain None.
      max_res : bool, optional
          If given a list of fmts, whether to return the highest
          resolution.
  
      Returns
      -------
      bit_res : int, or list
          The resolution(s) of the dat format(s) in bits.