Say I have a function J(x,y)[x =(0,4), y= (0,20)] and I want to make a plot with different combinations of (x,y) on the same plot. Is there a way to incorporate a for-loop inside the plot() function instead of having to solve for J(x,y) before plotting? I'm thinking something like plot(for x in range(0,4)....). 
Thank you!
 
    