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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 inside_cell( self, r ):
 """ Given a fractional-coordinate, if this lies outside the cell return the equivalent point inside the cell. Args: r (np.array):
 Fractional coordinates of a point (this may be outside the cell boundaries). Returns: (np.array):
 Fractional coordinates of an equivalent point, inside the cell boundaries. """

        centre = np.array( [ 0.5, 0.5, 0.5 ] )
        new_r = self.nearest_image( centre, r )
        return new_r