The 9 Dots Puzzle

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In this puzzle, you must connect all the dots using only 4 straight lines;
without lifting the pencil (ie: new lines must be connected to the previous one).
Each line can be as long or as short as you like; and a dot may be crossed by multiple lines.

Click anywhere on the board to set endpoint of the lines.
Can you solve this logic puzzle in one try?

This is an implementation of a popular classic puzzle
(read more at Wikipedia - warning: contains solution spoiler).

CGI/PHP Programing by F. Permadi, 2001