Deletes a commit.

        Params:
        * commit: A tuple, string, or Commit object representing the commit.

def delete_commit(self, commit):
        """
        Deletes a commit.

        Params:
        * commit: A tuple, string, or Commit object representing the commit.
        """
        req = proto.DeleteCommitRequest(commit=commit_from(commit))
        self.stub.DeleteCommit(req, metadata=self.metadata)