human
Complete the below
def lower_key(fn):

    '''':param fn: a key function
    :return:
    a function that wraps around the supplied key function to ensure
    the returned key is in lowercase.'
    '''
 Give me a the Python program you requested?
assistant
#Here is the Python program you requested.
    def lower(key):
        try:
            return key.lower()
        except AttributeError:
            return key
    return process_key(lower, fn)