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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 EvacuateNode(r, node, iallocator=None, remote_node=None, dry_run=False, early_release=False, mode=None, accept_old=False):
 """ Evacuates instances from a Ganeti node. @type node: str @param node: node to evacuate @type iallocator: str or None @param iallocator: instance allocator to use @type remote_node: str @param remote_node: node to evaucate to @type dry_run: bool @param dry_run: whether to perform a dry run @type early_release: bool @param early_release: whether to enable parallelization @type accept_old: bool @param accept_old: Whether caller is ready to accept old-style (pre-2.5) results @rtype: string, or a list for pre-2.5 results @return: Job ID or, if C{accept_old} is set and server is pre-2.5, list of (job ID, instance name, new secondary node); if dry_run was specified, then the actual move jobs were not submitted and the job IDs will be C{None} @raises GanetiApiError: if an iallocator and remote_node are both specified """


    if iallocator and remote_node:
        raise GanetiApiError("Only one of iallocator or remote_node can"
                             " be used")

    query = {
        "dry-run": dry_run,
    }

    if iallocator:
        query["iallocator"] = iallocator
    if remote_node:
        query["remote_node"] = remote_node

    if NODE_EVAC_RES1 in r.features:
        # Server supports body parameters
        body = {
            "early_release": early_release,
        }

        if iallocator is not None:
            body["iallocator"] = iallocator
        if remote_node is not None:
            body["remote_node"] = remote_node
        if mode is not None:
            body["mode"] = mode
    else:
        # Pre-2.5 request format
        body = None

        if not accept_old:
            raise GanetiApiError("Server is version 2.4 or earlier and"
                                 " caller does not accept old-style"
                                 " results (parameter accept_old)")

        # Pre-2.5 servers can only evacuate secondaries
        if mode is not None and mode != NODE_EVAC_SEC:
            raise GanetiApiError("Server can only evacuate secondary instances")

        if iallocator is not None:
            query["iallocator"] = iallocator
        if remote_node is not None:
            query["remote_node"] = remote_node
        if query:
            query["early_release"] = 1

    return r.request("post", "/2/nodes/%s/evacuate" % node, query=query,
                     content=body)