[This section](https://juliaapproximation.github.io/ApproxFun.jl/stable/usage/equations/#Partial-differential-equations-1) of the documentation says `# Δ is an alias for Laplacian()`, but it is not exported: ```julia-repl (@v1.8) pkg> st ApproxFun Status `~/.julia/environments/v1.8/Project.toml` [28f2ccd6] ApproxFun v0.13.0 julia> Δ ERROR: UndefVarError: Δ not defined julia> ApproxFun.Δ ConcreteLaplacian : ApproxFunBase.UnsetSpace() → ApproxFunBase.UnsetSpace() ```