--- a/src/Grids/mapped_grid.jl	Wed Oct 02 08:51:37 2024 +0200
+++ b/src/Grids/mapped_grid.jl	Tue Oct 22 08:50:23 2024 +0200
@@ -173,6 +173,8 @@
 function normal(g::MappedGrid, boundary)
     b_indices = boundary_indices(g, boundary)
     σ = _boundary_sign(component_type(g), boundary)
+
+    # TODO: Refactor this when `boundary_indices(g, ...)` has been made iterable.
     return map(jacobian(g)[b_indices...]) do ∂x∂ξ
         ∂ξ∂x = inv(∂x∂ξ)
         k = grid_id(boundary)
@@ -180,6 +182,11 @@
     end
 end
 
+"""
+    normal(g::MappedGrid, boundary, i...)
+
+The outward pointing normal to the specified boundary in grid point `i`.
+"""
 function normal(g::MappedGrid, boundary, i...)
     σ = _boundary_sign(component_type(g), boundary)
     ∂ξ∂x = inv(jacobian(g)[i...])