“…Some of these computations are known. The case of the plane is treated by Arnold in , the case of a once‐punctured orientable surface by Bödigheimer–Cohen in , the case of the sphere by Salvatore in (see also ), the case of the real projective plane by Wang in , and the case of a general closed nonorientable surface by the second author in . In addition, during the writing of this work, the authors learned of two independent computations in the case of the torus, due to Maguire and Schiessl , respectively.…”