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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 set_branch(self, commit, branch_name):
 """ Sets a commit and its ancestors as a branch. Params: * commit: A tuple, string, or Commit object representing the commit. * branch_name: The name for the branch to set. """

        res = proto.SetBranchRequest(commit=commit_from(commit), branch=branch_name)
        self.stub.SetBranch(res, metadata=self.metadata)