This function returns the filter function of @var{process}.
@end defun
+In case the process's output needs to be passed to several filters, you can
+use @code{add-function} to combine an existing filter with a new one.
+@xref{Advising Functions}.
+
Here is an example of the use of a filter function:
@smallexample
periods. The former specifies a period measured in seconds and the
latter specifies one measured in milliseconds. The two time periods
thus specified are added together, and @code{accept-process-output}
-returns after that much time, whether or not there has been any
+returns after that much time, even if there is no
subprocess output.
The argument @var{millisec} is obsolete (and should not be used),
speech synthesis.
The function @code{accept-process-output} returns non-@code{nil} if it
-did get some output, or @code{nil} if the timeout expired before output
+got output from @var{process}, or from any process if @var{process} is
+@code{nil}. It returns @code{nil} if the timeout expired before output
arrived.
@end defun
This function returns the sentinel of @var{process}.
@end defun
+In case a process status changes need to be passed to several sentinels, you
+can use @code{add-function} to combine an existing sentinel with a new one.
+@xref{Advising Functions}.
+
@defun waiting-for-user-input-p
While a sentinel or filter function is running, this function returns
non-@code{nil} if Emacs was waiting for keyboard input from the user at