<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def setup(addr, user, remote_path, local_key=None):
 """Setup the tunnel"""

    port = find_port(addr, user)

    if not port or not is_alive(addr, user):
        port = new_port()

        scp(addr, user, __file__, '~/unixpipe', local_key)

        ssh_call = ['ssh', '-fL%d:127.0.0.1:12042' % port,
                    '-o', 'ExitOnForwardFailure=yes',
                    '-o', 'ControlPath=~/.ssh/unixpipe_%%r@%%h_%d' % port,
                    '-o', 'ControlMaster=auto',
                    '%s@%s' % (user, addr,), 'python', '~/unixpipe',
                    'server', remote_path]
        if local_key:
            ssh_call.insert(1, local_key)
            ssh_call.insert(1, '-i')

        subprocess.call(ssh_call)
        # XXX Sleep is a bad way to wait for the tunnel endpoint
        time.sleep(1)

    return port