python if regex in string code example

Example 1: check if valid regex string python

import re
string = '['
try:
    re.compile(string)
    is_valid = True
except re.error:
    is_valid = False

Example 2: re contains

fullstring = "StackAbuse"
substring = "tack"

if substring in fullstring:
    print "Found!"
else:
    print "Not found!"