Regular expression generator for mandatory characters in arbitrary order.

mandatory_arbitrary.py

from itertools import permutations
import re

def generate_mandatory_arbitrary(content):
    pattern_string = '('
    for p in permutations(content):
        pattern_string += '(.*'
        for i in p:
            pattern_string += '{}.*'.format(i)
        pattern_string += ')|'
    return pattern_string[:-1] + ')'

print(generate_mandatory_arbitrary('abc'))