Function: _(_)
Section: symbolic_operators
Help: f(a,b,...): evaluate the function f on a,b,...
Description:
 (gen):gen          closure_callgenall($1, 0)
 (gen,gen):gen      closure_callgen1($1, $2)
 (gen,gen,gen):gen  closure_callgen2($1, $2, $3)
 (gen,gen,...):gen  closure_callgenall($1, ${nbarg 1 sub}, $3)
