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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 ystep(self):
 """This method is inserted into the inner cbpdn object, replacing its own ystep method, thereby providing a hook for applying the additional steps necessary for the AMS method. """


        # Extract AMS part of ystep argument so that it is not
        # affected by the main part of the ystep
        amidx = self.index_addmsk()
        Yi = self.cbpdn.AX[amidx] + self.cbpdn.U[amidx]
        # Perform main part of ystep from inner cbpdn object
        self.inner_ystep()
        # Apply mask to AMS component and insert into Y from inner
        # cbpdn object
        Yi[np.where(self.W.astype(np.bool))] = 0.0
        self.cbpdn.Y[amidx] = Yi