pause pause mode, invoke keyboard

## Description

Switch to the `pause` mode; inserted in the code of a function, `pause` interrupts the execution of the function: one receives a prompt symbol which indicates the level of the `pause` (e.g. `-1->`). The user is then in a new workspace in which all the lower-level variables (and in particular all the variable of the function) are available. To return to the calling workspace enter `return`.

In this mode, `[...]=return(...)` returns the variables of the argument `(...)` to the calling workspace with names in the output `[...]`. Otherwise, the lower-level variables are protected and cannot be modified.

The `pause` is extremely useful for debugging purposes.

This mode is killed by the command `abort`.

## Examples

        function c=foo(b)
        a=42+b
        disp("Thanks to the pause, you can investigate if ''a'' has the right value");
        disp("Value can be changed too if needed.");
        pause
        c=a+2
        endfunction

        foo(2)

## See also

- halt
- return
- abort
- quit
- whereami
- where
- sleep