import re

m = re.search(r"a+", "caaab")
assert m.group(0) == "aaa"

assert re.match(r"a+", "caaab") is None
m = re.match(r"a+", "aaaab")
assert m.group(0) == "aaaa"

assert re.sub("a", "z", "caaab") == "czzzb"
assert re.sub("a+", "z", "caaab") == "czb"

assert re.sub("a", lambda m: m.group(0) * 2, "caaab") == "caaaaaab"

m = re.match(r"(\d+)\.(\d+)", "24.1632")
assert m.groups() == ('24', '1632')