<!-- BUGS: Please use this template. --> **TypeScript Version:** 2.1.0-dev.20160729 **Code** ``` ts interface A { focus: (force: boolean) => void } interface B { focus: () => void } let instance: A | B instance.focus(true); ``` **Expected behavior:** No compilation error at least at 2.1.0-dev.20160716 **Actual behavior:** TS2349: Cannot invoke an expression whose type lacks a call signature.