Added check for # of args.
Updated script for Lesson 01.
Merge branch 'lesson01'
Updated script for Lesson 02.
Merge branch 'lesson02'
Updated script for Lesson 03.
Merge branch 'lesson03'
Updated script for Lesson 04.
Merge branch 'lesson04'
Updated script for Lesson 05.
Merge branch 'lesson05'
Updated script for Lesson 06.
Merge branch 'lesson06'