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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def list_(name=None, runas=None):
    '''
    Run launchctl list and return the output

    :param str name: The name of the service to list

    :param str runas: User to run launchctl commands

    :return: If a name is passed returns information about the named service,
        otherwise returns a list of all services and pids
    :rtype: str

    CLI Example:

    .. code-block:: bash

        salt '*' service.list
        salt '*' service.list org.cups.cupsd
    '''
    if name:
        # Get service information and label
        service = _get_service(name)
        label = service['plist']['Label']

        # we can assume if we are trying to list a LaunchAgent we need
        # to run as a user, if not provided, we'll use the console user.
        if not runas and _launch_agent(name):
            runas = __utils__['mac_utils.console_user'](username=True)

        # Collect information on service: will raise an error if it fails
        return launchctl('list',
                         label,
                         return_stdout=True,
                         runas=runas)

    # Collect information on all services: will raise an error if it fails
    return launchctl('list',
                     return_stdout=True,
                     runas=runas)