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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 initialize(self, calc_reg):
 """ Initialize the simulation. Organize calculations by dependency. :param calc_reg: Calculation registry. :type calc_reg: :class:`~simkit.core.calculation.CalcRegistry` """

        self._isinitialized = True
        # TODO: if calculations are edited, loaded, added, etc. then reset
        self.calc_order = topological_sort(calc_reg.dependencies)