计算Fisher的函数，根据Fisher可以计算出克罗美下界-Fisher s exact test is a statistical test used to determine if there are nonrandom associations between two categorical variables[1].

　　 The job of Fisher s exact test with 2 x 2 or 2x 3 contingency table is already easily done by others. However, the one with n x m contingency table hasn t found , or with bad computation.

　　 This function efficiently deals with Fisher s exact test with n x m contingency table.

　　 As for the function :