code: def fisher_mean(dec=None, inc=None, di_block=None):
      
      if di_block is None:
          di_block = make_di_block(dec, inc)
          return pmag.fisher_mean(di_block)
      else:
          return pmag.fisher_mean(di_block)
docs: Calculates the Fisher mean and associated parameters from either a list of
      declination values and a separate list of inclination values or from a
      di_block (a nested list a nested list of [dec,inc,1.0]). Returns a
      dictionary with the Fisher mean and statistical parameters.
  
      Parameters
      ----------
      dec : list of declinations or longitudes
      inc : list of inclinations or latitudes
      di_block : a nested list of [dec,inc,1.0]
          A di_block can be provided instead of dec, inc lists in which case it
          will be used. Either dec, inc lists or a di_block need to be provided.
  
      Returns
      -------
      fisher_mean : dictionary containing the Fisher mean parameters
  
      Examples
      --------
      Use lists of declination and inclination to calculate a Fisher mean:
  
      >>> ipmag.fisher_mean(dec=[140,127,142,136],inc=[21,23,19,22])
      {'alpha95': 7.292891411309177,
      'csd': 6.4097743211340896,
      'dec': 136.30838974272072,
      'inc': 21.347784026899987,
      'k': 159.69251473636305,
      'n': 4,
      'r': 3.9812138971889026}
  
      Use a di_block to calculate a Fisher mean (will give the same output as the
      example with the lists):
  
      >>> ipmag.fisher_mean(di_block=[[140,21],[127,23],[142,19],[136,22]])