re group match

import re

RE_PATTERNS= re.compile(r"^#(\d+)|^Issue\s#(\d+)|^Issue#(\d+)", flags=re.MULTILINE | re.IGNORECASE)


test_messages = [
    """#123""",
    """Issue #123""",
    """Issue#123"""
]


for message in test_messages:
    t1, t2, t3 = RE_PATTERNS.match(message).groups()
    if t1 is not None:
        print RE_PATTERNS.sub(r"prefix-\1", message)
    if t2 is not None:
        print RE_PATTERNS.sub(r"prefix-\2", message)
    if t3 is not None:
        print RE_PATTERNS.sub(r"prefix-\3", message)