docs: async def _write_ssl(self):
          """
          Flush outgoing data which OpenSSL put in our BIO to the transport.
          """
          pending = lib.BIO_ctrl_pending(self.write_bio)
          if pending > 0:
              result = lib.BIO_read(self.write_bio, self.write_cdata, len(self.write_cdata))
              await self.transport._send(ffi.buffer(self.write_cdata)[0:result])
              self.__tx_bytes += result
              self.__tx_packets += 1