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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 dv(self, orb):
 """Computation of the velocity increment in the reference frame of the orbit Args: orb (Orbit):
 Return: numpy.array: Velocity increment, length 3 """


        orb = orb.copy(form="cartesian")

        if self.frame == "QSW":
            mat = to_qsw(orb).T
        elif self.frame == "TNW":
            mat = to_tnw(orb).T
        else:
            mat = np.identity(3)

        # velocity increment in the same reference frame as the orbit
        return mat @ self._dv