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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 add(self, sim, module, package=None):
 """ Add simulation to layer. """

        super(Simulations, self).add(sim, module, package)
        # only update layer info if it is missing!
        if sim not in self.layer:
            # copy simulation source parameters to :attr:`Layer.layer`
            self.layer[sim] = {'module': module, 'package': package}