def int_or_none(v):
return v if v is None else int(v)
+
+
+def parse_duration(s):
+ if s is None:
+ return None
+
+ m = re.match(
+ r'(?:(?:(?P<hours>[0-9]+):)?(?P<mins>[0-9]+):)?(?P<secs>[0-9]+)$', s)
+ if not m:
+ return None
+ res = int(m.group('secs'))
+ if m.group('mins'):
+ res += int(m.group('mins')) * 60
+ if m.group('hours'):
+ res += int(m.group('hours')) * 60 * 60
+ return res