Change a string's characters from one base to another.
    Return the re-encoded string

def changebase(string, frm, to, minlen=0):
    """
    Change a string's characters from one base to another.
    Return the re-encoded string
    """
    if frm == to:
        return lpad(string, get_code_string(frm)[0], minlen)

    return encode(decode(string, frm), to, minlen)