utils: example of rmlines

Ref #24, #109

Author: iblislin

src/utils.jl

@@ -57,6 +57,14 @@ iscall(ex, f) = isexpr(ex, :call) && ex.args[1] == f
 Remove the line nodes from a block or array of expressions.
 
 Compare `quote end` vs `rmlines(quote end)`
+
+### Examples
+
+To work with nested blocks:
+
+```julia
+prewalk(rmlines, ex)
+```
 """
 rmlines(x) = x
 function rmlines(x::Expr)