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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 _in_polygon(points, polygon):
 """Return the points that are inside a polygon."""

    from matplotlib.path import Path
    points = _as_array(points)
    polygon = _as_array(polygon)
    assert points.ndim == 2
    assert polygon.ndim == 2
    if len(polygon):
        polygon = np.vstack((polygon, polygon[0]))
    path = Path(polygon, closed=True)
    return path.contains_points(points)