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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 _increment_rigid_ids(self, increment):
 """Increment the rigid_id of all rigid Particles in a Compound Adds `increment` to the rigid_id of all Particles in `self` that already have an integer rigid_id. """

        for particle in self.particles():
            if particle.rigid_id is not None:
                particle.rigid_id += increment