An invalid number of arguments was given when calling a closure. Erroneous code example: ```compile_fail,E0057 let f = |x| x * 3; let a = f(); // invalid, too few parameters let b = f(4); // this works! let c = f(2, 3); // invalid, too many parameters ``` When invoking closures or other implementations of the function traits `Fn`, `FnMut` or `FnOnce` using call notation, the number of parameters passed to the function must match its definition. A generic function must be treated similarly: ``` fn foo(f: F) { f(); // this is valid, but f(3) would not work } ```