+=head2 Standard Shell Functions
+
+=head3 quoted_string
+
+Quote a string which will be consumed as a goal expression. This is
+typically used from within goal functions which return expressions
+(ie. ones which do I<not> have an explicit C<returning> declaration).
+You must not use this shell function with functions that are marked as
+C<returning string> or C<returning strings>.
+
+=head3 print_green
+
+Echo a string in green. Useful for success/OK messages.
+
+=head3 print_red
+
+Echo a string in red. Useful for error messages.
+