[docs] [issue17854] symmetric difference operation applicable to more than two sets

Terry J. Reedy added the comment: If you take the union/intersection/symmetric difference of n sets, the result is a set with all items that appears in one/all/an odd number of the n sets. The union and intersection methods actually accept n inputs, because the result is obvious, useful, and can be obtained faster that with n-1 binary operations. The symmetric_difference method does not, I presume because the result in not obvious (but that cuts both ways), not known to be useful, and perhaps would not be much faster than than n-1 binary operations. ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue17854> _______________________________________