utf7.py

import string

b64table = string.ascii_uppercase + string.ascii_lowercase + string.digits + "+/"


def to_utf7(s):
    ret = ""
    for c in s:
        n = ord(c)
        bits = f"{n:016b}00"
        idxs = [int(bits[i : i + 6], 2) for i in range(0, len(bits), 6)]
        ret += "+" + "".join(b64table[x] for x in idxs) + "-"
    return ret


s = "Hello World!"
print(to_utf7(s))
print(to_utf7(s).encode().decode("utf-7") == s)