code: def _rm_compute_leading_space(space_s_pres_split):
    
    i = 0
    c = 0
    while (i < len(space_s_pres_split) and
           (space_s_pres_split[i].isspace() or
           (space_s_pres_split[i] == ""))):
      c += len(space_s_pres_split[i])
      i += 1
    return c
docs: count the number of spaces that precede a non-space token (not including
    empty string tokens) in a string.
  
    :param space_s_pres_split: the string, split into tokens around spaces,
                               but with the spaces conserved as tokens.