'Initialize a client.'

def __init__(self, config, account_, auth, installer, acme=None):

    self.config = config
    self.account = account_
    self.auth = auth
    self.installer = installer
    if ((acme is None) and (self.account is not None)):
        acme = acme_from_config_key(config, self.account.key)
    self.acme = acme
    if (auth is not None):
        self.auth_handler = auth_handler.AuthHandler(auth, self.acme, self.account, self.config.pref_challs)
    else:
        self.auth_handler = None
