This example denotes that how to open new location.
Thats the file that keeps a record of everywhere you have been during that
particular web browsing session. (1) sends it forward one step, (-1) sends
you backwards one step. If you would like, you can raise or lower those numbers.
Setting it to (-4) will take your user back four pages if he or she has that
many page in their history file. If not, then the button will not function.