Make PROCESS see end-of-file in its input.
EOF comes after any text already sent to it.
PROCESS may be a process, a buffer, the name of a process or buffer, or
nil, indicating the current buffer's process.
If PROCESS is a network connection, or is a process communicating
through a pipe (as opposed to a pty), then you cannot send any more
text to PROCESS after you call this function.
If PROCESS is a serial process, wait until all output written to the
process has been transmitted to the serial port. (fn &optional PROCESS)