Dead Code

[lychjck]

`

// Write breaks down a L2CAP SDU into segmants [Vol 3, Part A, 7.3.1]

func (c *Conn) Write(sdu []byte) (int, error) {
if len(sdu) > c.txMTU {
return 0, errors.Wrap(io.ErrShortWrite, "payload exceeds mtu")
}
plen := len(sdu)
if plen > c.txMTU {
plen = c.txMTU
}
b := make([]byte, 4+plen)
binary.LittleEndian.PutUint16(b[0:2], uint16(len(sdu)))
binary.LittleEndian.PutUint16(b[2:4], cidLEAtt)
if c.leFrame {
binary.LittleEndian.PutUint16(b[4:6], uint16(len(sdu)))
copy(b[6:], sdu)
} else {
copy(b[4:], sdu)
}
sent, err := c.writePDU(b)
if err != nil {
return sent, err
}
sdu = sdu[plen:]

for len(sdu) > 0 {
	plen := len(sdu)
	if plen > c.txMTU {
		plen = c.txMTU
	}
	n, err := c.writePDU(sdu[:plen])
	sent += n
	if err != nil {
		return sent, err
	}
	sdu = sdu[plen:]
}
return sent, nil

}`

in conn.go Write function,when len(sdu) > c.txMTU ,function is return
What is the meaning of the following fragments?