Read at least one byte of cooked data unless EOF is hit.

        Return b'' if EOF is hit.

def read_some(self):
        """Read at least one byte of cooked data unless EOF is hit.

        Return b'' if EOF is hit.
        """
        yield from self.process_rawq()
        while not self.cookedq and not self.eof:
            yield from self.fill_rawq()
            yield from self.process_rawq()
        buf = self.cookedq
        self.cookedq = b''
        return buf