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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 entries_in_tree_oid(self, prefix, tree_oid):
 """Find the tree at this oid and return entries prefixed with ``prefix``"""

        try:
            tree = self.git.get_object(tree_oid)
        except KeyError:
            log.warning("Couldn't find object {0}".format(tree_oid))
            return empty
        else:
            return frozenset(self.entries_in_tree(prefix, tree))