code: def _rm_extract_sequence_and_name(alig_str_parts, s1_name, s2_name):
    
    # first, based on the number of parts we have we'll guess whether its a
    # reverse complement or not
    if len(alig_str_parts) == 4:
      # expect the first element to amtch something..
      nm = alig_str_parts[0]
      seq = alig_str_parts[2]
    elif len(alig_str_parts) == 5:
      # expect the second element to match something...
      nm = alig_str_parts[1]
      seq = alig_str_parts[3]
    else:
      raise AlignmentIteratorError("failed parsing alignment line '" +
                                   " ".join(alig_str_parts) + "'; reason: " +
                                   "expected this line to have 4 or 5 " +
                                   "elements, but it has " +
                                   str(len(alig_str_parts)))
    if _rm_name_match(nm, s1_name):
      return s1_name, seq
    elif _rm_name_match(nm, s2_name):
      return s2_name, seq
    else:
      raise AlignmentIteratorError("failed parsing alignment line '" +
                                   " ".join(alig_str_parts) + "'; reason: " +
                                   "extracted alignment name (" + nm + ") " +
                                   "did not match either sequence name from " +
                                   "header line (" + s1_name + " or " +
                                   s2_name + ")")
docs: parse an alignment line from a repeatmasker alignment and return the name
    of the sequence it si from and the sequence portion contained in the line.
  
    :param alig_str_parts: the alignment string, split around whitespace as list
    :param s1_name: the name of the first sequence in the alignment this line is
                    from
    :param s2_name: the name of the second sequence in the alignment this line is
                    from
    :return: a tuple of name and sequence string; name will always be either
             s1_name or s2_name
    :raise AlignmentIteratorError: if the line doesn't have the expected number
                                   of elements, or the name does not match
                                   either of s1_name or s2_name