import base64

s = '49276d206b696c6c696e6720796f757220627261696e206c696b65206120706f69736f6e6f7573206d757368726f6f6d'
expected = 'SSdtIGtpbGxpbmcgeW91ciBicmFpbiBsaWtlIGEgcG9pc29ub3VzIG11c2hyb29t'

def hex_str_to_base64(s):
    return base64.b64encode(s.decode('hex'))

assert hex_str_to_base64(s) == expected