human
Complete this python program:
def censor_non_alphanum(s):
assistant
#Here is the Python code you requested.

    """Returns s with all non-alphanumeric characters replaced with *
    Parameters
    s : str
    The string to be censored.
    Returns
    output : str
    The censored version of `s`
    """
    def censor(ch):
        if (((ch >= 'A') and (ch <= 'z')) or ((ch >= '0') and (ch <= '9'))):
            return ch
        return '*'
    return ''.join((censor(ch) for ch in s))