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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 set_listener_policy(name, port, policies=None, region=None, key=None,
                        keyid=None, profile=None):
    '''
    Set the policies of an ELB listener.

    .. versionadded:: 2016.3.0

    CLI example:

    .. code-block:: Bash

        salt myminion boto_elb.set_listener_policy myelb 443 "[policy1,policy2]"
    '''
    conn = _get_conn(region=region, key=key, keyid=keyid, profile=profile)

    if not exists(name, region, key, keyid, profile):
        return True
    if policies is None:
        policies = []
    try:
        conn.set_lb_policies_of_listener(name, port, policies)
        log.info('Set policies %s on ELB %s listener %s', policies, name, port)
    except boto.exception.BotoServerError as e:
        log.info('Failed to set policy %s on ELB %s listener %s: %s',
                 policies, name, port, e.message,
                 exc_info_on_loglevel=logging.DEBUG)
        return False
    return True