ng WILL NOT WORK because the lines sent before the setecho
        will be lost::

            p = pexpect.spawn('cat')
            p.sendline('1234')
            p.setecho(False) # Turn off tty echo
            p.sendline('abcd') # We will set this only once (echoed by cat).
            p.sendline('wxyz') # We will set this only once (echoed by cat)
            p.expect(['1234'])
            p.expect(['1234'])
            p.expect(['abcd'])
            p.expect(['wxyz'])


        Not supported on platforms where ``isatty()`` returns False.
        )