<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def make_client(zhmc, userid=None, password=None):
 """ Create a `Session` object for the specified HMC and log that on. Create a `Client` object using that `Session` object, and return it. If no userid and password are specified, and if no previous call to this method was made, userid and password are interactively inquired. Userid and password are saved in module-global variables for future calls to this method. """


    global USERID, PASSWORD  # pylint: disable=global-statement

    USERID = userid or USERID or \
        six.input('Enter userid for HMC {}: '.format(zhmc))
    PASSWORD = password or PASSWORD or \
        getpass.getpass('Enter password for {}: '.format(USERID))

    session = zhmcclient.Session(zhmc, USERID, PASSWORD)
    session.logon()
    client = zhmcclient.Client(session)
    print('Established logged-on session with HMC {} using userid {}'.
          format(zhmc, USERID))
    return client