def _rm_compute_leading_space_alig(space_pres_split, seq):
c = <NUM_LIT:0><EOL>for i in range(<NUM_LIT:0>, len(space_pres_split)):<EOL><INDENT>if space_pres_split[i] == seq:<EOL><INDENT>break<EOL><DEDENT>c += len(space_pres_split[i])<EOL><DEDENT>return c<EOL>
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.