Plotting bivariate kde

kde.jl

using RDatasets, KernelDensity
faithful = dataset("datasets", "faithful");
a = kde((faithful[:Eruptions],faithful[:Waiting]));

#How do I get cartesian product of x and y, such that it represents same coordinates as reshaped color?
x = collect(a.x) #256-element Array{Float64,1}
y = collect(a.y) #256-element Array{Float64,1}
color = reshape(a.density, 65536) #65536-element Array{Float64,1}