def _convert_date(date_string, date_format):
if date_format != '<STR_LIT>':<EOL><INDENT>return datetime.strptime(date_string, date_format).timestamp()<EOL><DEDENT>else:<EOL><INDENT>return float(date_string)<EOL><DEDENT>
Convert a date in a given format to epoch time. Mostly a wrapper for
datetime's strptime.