code: def parse_atfile_cat(input):
      
      with open(input[1:]) as f:
          catlist = []
          catdict = {}
          for line in f.readlines():
              if line[0] == '#' or not line.strip():
                  continue
  
              lspl = line.split()
              if len(lspl) > 1:
                  catdict[lspl[0]] = lspl[1:]
                  catlist.append(lspl[1:])
              else:
                  catdict[lspl[0]] = None
                  catlist.append(None)
  
      return catlist, catdict
docs: Return the list of catalog filenames specified as part of the input @-file