### Plotting x, free variable error

I was plotting sin(x)/x and also wanted a seperate plot of sin(x) and x so I could visualize those components as well. However I get an error when plotting x saying "free variable x -> x". If I add a coefficient to h(x) such as `h(x) = 1.0001*x`

then it works fine.

This is the code I am using:

```
f(x) = sin(x)/x
g(x) = sin(x)
h(x) = x
fig1 = plot(f,-10,10,rgbcolor='green')
fig2 = plot(g,-10,10,rgbcolor='purple')
fig3 = plot(h,-10,10,rgbcolor='red')
figure = fig1 + fig2 + fig3
show(figure,xmin=-10,xmax=10,ymin=-10,ymax=10,figsize=[8,8],fontsize=20)
```