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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_max_rad_npnp(self):
 """Finds the maximum radius and npnp in the force field. Returns ------- (max_rad, max_npnp):
 (float, float) Maximum radius and npnp distance in the loaded force field. """

        max_rad = 0
        max_npnp = 0
        for res, atoms in self.items():
            if res != 'KEY':
                for atom, ff_params in self[res].items():
                    if max_rad < ff_params[1]:
                        max_rad = ff_params[1]
                    if max_npnp < ff_params[4]:
                        max_npnp = ff_params[4]
        return max_rad, max_npnp