Member predicate Impl::Call::getArgument

Gets the argument at position pos of this call.

Examples:

foo(42, "bar");    // `42` is argument 0 and `"bar"` is argument 1
foo.bar(42);       // `foo` is receiver and `42` is argument 0
Foo::bar(foo, 42); // `foo` is receiver and `42` is argument 0
x + y;             // `x` is receiver and `y` is argument 0
-x;                // `x` is receiver
x[y];              // `x` is receiver and `y` is argument 0