<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def show():
 """ Shows the URL of the current cloud server or throws an error if no cloud server is selected """

    utils.check_for_cloud_server()
    click.echo("Using cloud server at \"{}\"".format(
        config["cloud_server"]["url"]
    ))
    if config["cloud_server"]["username"]:
        click.echo(
            "Logged in as user \"{}\"".format(config["cloud_server"]["username"])
        )
    if config["cloud_server"]["farm_name"]:
        click.echo(
            "Using farm \"{}\"".format(config["cloud_server"]["farm_name"])
        )