<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _apply_transformation(inputs):
 """ Helper method for multiprocessing of apply_transformation. Must not be in the class so that it can be pickled. Args: inputs: Tuple containing the transformed structure, the transformation to be applied, a boolean indicating whether to extend the collection, and a boolean indicating whether to clear the redo Returns: List of output structures (the modified initial structure, plus any new structures created by a one-to-many transformation) """

    ts, transformation, extend_collection, clear_redo = inputs
    new = ts.append_transformation(transformation, extend_collection,
                                   clear_redo=clear_redo)
    o = [ts]
    if new:
        o.extend(new)
    return o