15.12.2.5 define k

[Rafkind, Jon]

The third sentence of 15.12.2.5 implicitly defines k as exp1..expk. It
would be nice if k was explicitly defined before that. I had a hard time
finding the definition of k while reading the three cases about m1 vs m2.

  Let k be the number of argument expressions for an invocation and
exp1...expk be the list of arguments. One method m1 is more specific
than m2, if any of the following are true: