Write a script named number lines.by. This script creates a program listing from a source program. This script should: Prompt the user for the names of two files. The input file name would be the name of the script itself, but be careful to use a different output filename! The script copies the lines of text from the input file to the output file, numbering each line as it goes. The line numbers should be right-justified in 4 columns, so that the format of a line in the output file looks like this example:

Below are the 5 things that you may find useful

1. Number + [enter]
Go to the slide number. This is useful when there are large number of slides in your presentation and you want to move to some particular number directly

2. B or Period
Display a blank black slide or return to the presentation from blank black slide
Similarly use W or Comma - to display blank white slide.
This is useful when you want to use temporary slide while presenting a presentation.

3. Esc or hyphen
To end a presentation

4. Shift + F9
Show or the hide the grid. Useful when aligning the objects on screen

5. H
go to next slide if next slide is hidden. This is useful when you have one slides but don't know whether it would be apt while presenting. So in such case make that hidden. And while presenting use 'H' if that slide can be useful to your audience.