* When data is received through one of these pipes, \var{h} or \var{errh}
* is called with that data. When the pipe is closed, the handler is called
* with \code{nil} argument. The PID of the new process is returned, or
* When data is received through one of these pipes, \var{h} or \var{errh}
* is called with that data. When the pipe is closed, the handler is called
* with \code{nil} argument. The PID of the new process is returned, or