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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 collective_dr_squared( self ):
 """ Squared sum of total displacements for these atoms. Args: None Returns: (Float):
 The square of the summed total displacements for these atoms. """

        return sum( np.square( sum( [ atom.dr for atom in self.atoms ] ) ) )