def read(self, amount: int=-1) -> bytes:
        '''Read data.'''
        assert self._state == ConnectionState.created, \
            'Expect conn created. Got {}.'.format(self._state)

        data = yield from \
            self.run_network_operation(
                self.reader.read(amount),
                close_timeout=self._timeout,
                name='Read')

        return data
Read data.