Evaluate code in the context of the frame.

def eval(self, code, mode="single"):
        """Evaluate code in the context of the frame."""
        if isinstance(code, string_types):
            if PY2 and isinstance(code, text_type):  # noqa
                code = UTF8_COOKIE + code.encode("utf-8")
            code = compile(code, "<interactive>", mode)
        return eval(code, self.globals, self.locals)