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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 ids(self):
 """A frozen set of all unique IDs in the file."""

        as_list = [seq.description.split()[0] for seq in self]
        as_set = frozenset(as_list)
        assert len(as_set) == len(as_list)
        return as_set