many edits

quarto/integral_vector_calculus/stokes_theorem.qmd

@@ -685,7 +685,6 @@ The constant $A$ just sets the scale, the parameter $n$ has a qualitative effect
 
 ```{julia}
 #| hold: true
-gr() # pyplot doesn't like the color as specified below.
 n = 2
 f(r,theta) = r^n * cos(n*theta)
 g(r, theta) = r^n * sin(n*theta)
@@ -698,7 +697,6 @@ f(v) = f(v...); g(v)= g(v...)
 xs = ys = range(-2,2, length=50)
 p = contour(xs, ys, f∘Φ, color=:red, legend=false, aspect_ratio=:equal)
 contour!(p, xs, ys, g∘Φ, color=:blue, linewidth=3)
-#pyplot()
 p
 ```