Update docstring

src/qn/flux.jl

@@ -68,10 +68,11 @@ allfluxequal(T::Tensor) = allequal(flux(T, b) for b in nzblocks(T))
 
 Check that fluxes of all non-zero blocks of a blocked or symmetric Tensor
 are equal. Throws an error if one or more blocks have a different flux.
+If the tensor is dense (is not blocked) then `checkflux` returns `nothing`.
 """
-function checkflux(T::Tensor) 
+function checkflux(T::Tensor)
   (!hasqns(T) || isempty(T)) && return nothing
-  allfluxequal(T) ? nothing : error("Fluxes not all equal")
+  return allfluxequal(T) ? nothing : error("Fluxes not all equal")
 end
 
 """