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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 store(self):
        '''
        Record the current value of each variable X named in track_vars in an
        attribute named X_hist.

        Parameters
        ----------
        none

        Returns
        -------
        none
        '''
        for var_name in self.track_vars:
            value_now = getattr(self,var_name)
            getattr(self,var_name + '_hist').append(value_now)