Question: error trying to duplicate from example that professor gave out

Hi, this is what I did and got an error. 

with (plots):

col := ["Red", "Green", "Blue", "Orange", "Teal", "Azure", "BlueViolet", "Yellow", "DarkOliveGreen", "DarkRed"]

for i from 1 to 10 do z [i]:=implicitplot (x^((1/(3)))* (y(x)^(2)+ 5* y(x)) + 3 *(x^(2)+y(x)^(2))*sin(xy(x)),  i^(),x = -10...10,  y= -20...20, color = col[i], numpoints = 2000) od:
 

Error, illegal use of an object as a name                     

for i from 1 to 10 do z [i]:=implicitplot (x^((1/(3)))* (y(x)^(2)+ 5* y(x)) + 3 *(x^(2)+y(x)^(2))*sin(xy(x)),  i^(),x = -10...10,  y= -20...20, color = col[i], numpoints = 2000) od:

I am trying to duplicate this example with my equations above.

First load up the plotting routines 

which contains the routine implicitplots for solving implicit functions of this form.  Set up an array of colours: 

Then generate 5 solutions for different values of c. 

 Numpoints species the number of points used in getting the solution.  This often has to be quite large if the solutions are to be smooth. Display the plots on a single graph