i am having a problem when trying to draw to an off-screen buffer and save as a .tiff. the code i am using is taken directly from the 'processing' book but am getting the error 'the function beginDraw() does not exist'

code:

2. PGraphics big;
3. int numWires = 3; //number of wires
4. 
   
5. void setup() {
6. 
   
7.   smooth();
8.   noLoop();
9.   big = createGraphics(4000, 1000, JAVA2D);
10.   beginDraw();
11.   for (int i = 0; i < numWires; i++) {
12.     int lineSpace = 1000/numWires;
13.     int lineHeight = 100+(i*lineSpace)+int(random(-30, 30));
14.     wire(0, lineHeight, 4000, lineHeight, int(random(2, 80)));
15.   }
16.   big.endDraw();
17.   big.save("big.tiff");
18. }

am new to processing and am probably doing something wrong, any help would be appreciated.

thanks