In netcat3, the interface value conn has the concrete type *net.TCPConn, which represents a TCP connection.
A TCP connection consists of two halves that may be closed independently using its CloseRead and CloseWrite methods.
Modify the main goroutine of netcat3 to close only the write half of the connection so that the program will continue to print the final echoes from the reverb1 server even after the standard input has been closed.
(Doing this for the reverb2 server is harder; see Exercise 8.4)