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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 _find_closest_trackpoint(self,R,vR,vT,z,vz,phi,interp=True,xy=False, usev=False):
 """For backward compatibility"""

        return self.find_closest_trackpoint(R,vR,vT,z,vz,phi,
                                            interp=interp,xy=xy,
                                            usev=usev)