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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 _soi(self, orb):
 """Evaluate the need for SOI transition, by comparing the radial distance between the considered body and the spacecraft If therer is no body in sight, default to central body. """


        for body in self.alt:
            soi = self.SOI[body.name]
            sph = orb.copy(frame=soi.frame, form='spherical')
            if sph.r < soi.radius:
                active = body
                break
        else:
            active = self.central

        return active