docs: def guess_input_handler(seqs, add_seq_names=False):
      """Returns the name of the input handler for seqs."""
      if isinstance(seqs, str):
          if '\n' in seqs:  # can't be a filename...
              return '_input_as_multiline_string'
          else:  # assume it was a filename
              return '_input_as_string'
  
      if isinstance(seqs, list) and len(seqs) and isinstance(seqs[0], tuple):
          return '_input_as_seq_id_seq_pairs'
  
      if add_seq_names:
          return '_input_as_seqs'
  
      return '_input_as_lines'