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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 require(self, *namespecs):
 """Return a bundle of the requested assets and their dependencies."""

        blacklist = set([n[1:] for n in namespecs if n.startswith('!')])
        not_blacklist = [n for n in namespecs if not n.startswith('!')]
        return Bundle(*[bundle for name, version, bundle
            in self._require_recursive(*not_blacklist) if name not in blacklist])