graph in july using Surface plot

using PyPlot
clf()
n = 100
x = range(-pi/2,stop=pi/2,length=n)
xgrid = repeat(x,n,1)
ygrid = repeat(x,1,n)
z = cos(xgrid).*cos(ygrid)
fig = figure("An example", figsize=(10,5))
ax = fig[:add_subplot](1,1,1, projection = "3d")
ax[:plot_surface](xgrid, ygrid, z)
fig = figure("An example", figsize=(10,5))
fig[:gca](projection = "3d")
plot_surface(xgrid, ygrid, z)
ax[:plot_surface](xgrid, ygrid, z, rstride=2,edgecolors="k", cstride=2,cmap=ColorMap("gray"), alpha=0.8, linewidth=0.25)
cp = ax[:contour](xgrid, ygrid, z, colors="black", linewidth=2.0)
ax[:clabel](cp, inline=1, fontsize=10)