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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 load_stencil_set(self, stencilset_name):
 """Return the Stencil Set from this template pack."""

        if stencilset_name not in self._stencil_sets:
            if stencilset_name not in self.manifest['stencil_sets'].keys():
                raise exc.FastfoodStencilSetNotListed(
                    "Stencil set '%s' not listed in %s under stencil_sets."
                    % (stencilset_name, self.manifest_path))
            stencil_path = os.path.join(
                self.path, 'stencils', stencilset_name)
            self._stencil_sets[stencilset_name] = (
                stencil_module.StencilSet(stencil_path))
        return self._stencil_sets[stencilset_name]