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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 remove_sources(self, sources):
 """ Remove sources from the decomposition. This function removes sources from the decomposition. Doing so invalidates currently fitted VAR models and connectivity estimates. Parameters sources : {slice, int, array of ints} Indices of components to remove. Returns ------- self : Workspace The Workspace object. Raises ------ RuntimeError If the :class:`Workspace` instance does not contain a source decomposition. """

        if self.unmixing_ is None or self.mixing_ is None:
            raise RuntimeError("No sources available (run do_mvarica first)")
        self.mixing_ = np.delete(self.mixing_, sources, 0)
        self.unmixing_ = np.delete(self.unmixing_, sources, 1)
        if self.activations_ is not None:
            self.activations_ = np.delete(self.activations_, sources, 1)
        self.var_model_ = None
        self.var_cov_ = None
        self.connectivity_ = None
        self.mixmaps_ = []
        self.unmixmaps_ = []
        return self