def marker_cycle(markers=None):
if markers:<EOL><INDENT>return itertools.cycle(markers)<EOL><DEDENT>return itertools.cycle(('<STR_LIT:o>', '<STR_LIT:x>', '<STR_LIT:+>', '<STR_LIT>', '<STR_LIT:D>', '<STR_LIT:H>', '<STR_LIT:1>'))<EOL>
An infinite iterator of the given (or default) markers