To draw a line, you can choose between drawing a full line or continuing from the last point of the previously drawn element.
You can draw a full line using the command below
line x y x y
This command will draw a single line between two x,y positions
line 10 10 -10 -10
You can also continue the previous line using cont
cont x y
line 10 10 -10 -10
line -10 -10 10 -10
Would draw the exact same thing as
line 10 10 -10 -10
cont 10 -10