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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 check_unused(intersection, duplicates, intersections):
 """Check if a "valid" ``intersection`` is already in ``intersections``. This assumes that * ``intersection`` will have at least one of ``s == 0.0`` or ``t == 0.0`` * At least one of the intersections in ``intersections`` is classified as ``COINCIDENT_UNUSED``. Args: intersection (.Intersection):
 An intersection to be added. duplicates (List[.Intersection]):
 List of duplicate intersections. intersections (List[.Intersection]):
 List of "accepted" (i.e. non-duplicate) intersections. Returns: bool: Indicates if the ``intersection`` is a duplicate. """

    for other in intersections:
        if (
            other.interior_curve == UNUSED_T
            and intersection.index_first == other.index_first
            and intersection.index_second == other.index_second
        ):
            if intersection.s == 0.0 and other.s == 0.0:
                duplicates.append(intersection)
                return True

            if intersection.t == 0.0 and other.t == 0.0:
                duplicates.append(intersection)
                return True

    return False