Sets location of the browser binary, either by string or
        ``FirefoxBinary`` instance.

def binary(self, new_binary):
        """Sets location of the browser binary, either by string or
        ``FirefoxBinary`` instance.

        """
        if not isinstance(new_binary, FirefoxBinary):
            new_binary = FirefoxBinary(new_binary)
        self._binary = new_binary