import hashlib
import base64


def my_hash(s):
    """A hash-like function that returns a string from a string input.
    It is not strictly a hash because the output have been encoded with
    base64 meaning that its size is not constant."""
    m = hashlib.sha256()
    m.update(s.encode('UTF-8'))
    ret = base64.b64encode(m.digest()[0:15]).decode('ASCII')
    return ret