def _rm_get_reference_coords_from_header(parts):
s = int(parts[<NUM_LIT:5>])<EOL>e = int(parts[<NUM_LIT:6>]) + <NUM_LIT:1><EOL>if (s >= e):<EOL><INDENT>raise AlignmentIteratorError("<STR_LIT>" +<EOL>"<STR_LIT:U+0020>".join(parts))<EOL><DEDENT>return (s, e)<EOL>
extract the reference (genomic sequence match) coordinates of a repeat
occurrence from a repeatmakser header line. An example header line is::

  239 29.42 1.92 0.97 chr1 11 17 (41) C XX#YY (74) 104 1 m_b1s502i1 4

the genomic start and end are always at positions 5 and 6 resepctively. In
the repeatmasker format, the end is inclusive, but in pyokit end coordinates
are exclusive, so we adjust it when we parse here.

:param parts: the header line, as a tokenized list.
:return: tuple of (start, end)