docs: def _rm_compute_leading_space_alig(space_pres_split, seq):
    """
    count the number of characters that precede the sequence in a repeatmasker
    alignment line. E.g. in the following line:
           '  chr1               11 CCCTGGAGATTCTTATT--AGTGATTTGGGCT 41'
    the answer would be 24.
  
    :param space_pres_split: the alignment line, split into tokens around spaces,
                             but with the spaces conserved as tokens.
    :param seq: the sequence token.
    """
    c = 0
    for i in range(0, len(space_pres_split)):
      if space_pres_split[i] == seq:
        break
      c += len(space_pres_split[i])
    return c