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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 _unwrap_to_layer(r, L, n=1):
 """For a set of points in a 2 dimensional periodic system, extend the set of points to tile the points up to to a given period. Parameters r: float array, shape (:, 2). Set of points. L: float array, shape (2,) System lengths. n: integer. Period to unwrap up to. Returns ------- rcu: float array, shape (:, 2). The set of points. tiled up to the periods at a distance `n` from the origin. """

    rcu = []
    for i_n in range(n + 1):
        rcu.extend(_unwrap_one_layer(r, L, i_n))
    return rcu