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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 _distance(self, x0, y0, x1, y1):
 """Utitlity function to compute distance between points."""

        dx = x1-x0
        dy = y1-y0
        # roll displacements across the borders
        if self.pix:
            dx[ dx > self.Lx/2 ] -= self.Lx
            dx[ dx < -self.Lx/2 ] += self.Lx
        if self.piy:
            dy[ dy > self.Ly/2 ] -= self.Ly
            dy[ dy < -self.Ly/2 ] += self.Ly
        return dx, dy