# contour and function definition

Hello

Let us consider this piece of code

var('x,y')

px=(x,-1,1)

py=(y,-1,1)

def V(x,y) :

if (x**2+y**2 <1) :

return(x+y+(abs(1-x**2-y**2))**(1/2))
else:
return(20)
W(x,y)=x+y+(abs(1-x**2-y

**2))**(1/2)

r=Graphics()

r+=contour_plot(W(x,y),px,py,contours=[1.70],fill=false,cmap=["red"])

r+=contour_plot(V(x,y),px,py,contours=[1.50],fill=false,cmap=["magenta"])

plot(r)

In 4.7, the level lines in magenta *and* red are displayed,
but in 4.8 only the red one appears.

- is this change expected ?
- how to let sage knowing the definition of the V function ?