- /// capture local variables, and macros are only allowed in item,
- /// statement or expression position, meaning this macro may be difficult to
- /// use in some situations.
+ /// capture local variables. Also, as a general rule, macros are only
+ /// allowed in item, statement or expression position. That means while
+ /// you may use this macro for referring to existing variables, functions or
+ /// modules etc, you cannot define a new one with it.