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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 delete_config(lines):
    '''
    Delete one or more config lines to the switch running config

    .. code-block:: bash

        salt '*' onyx.cmd delete_config 'snmp-server community TESTSTRINGHERE group network-operator'

    .. note::
        For more than one config deleted per command, lines should be a list.
    '''
    if not isinstance(lines, list):
        lines = [lines]
    try:
        sendline('config terminal')
        for line in lines:
            sendline(' '.join(['no', line]))

        sendline('end')
        sendline('copy running-config startup-config')
    except TerminalException as e:
        log.error(e)
        return False
    return True