+///
+/// Given the following
+///
+/// ```rust,ignore
+/// macro_rules! m { ($e:expr) => { f($e) }; }
+/// g(m!(0))
+/// ```
+///
+/// If called with a span of the call to `f` and a context of the call to `g` this will return a
+/// span containing `m!(0)`. However, if called with a span of the literal `0` this will give a span
+/// containing `0` as the context is the same as the outer context.
+///
+/// This will traverse through multiple macro calls. Given the following:
+///
+/// ```rust,ignore
+/// macro_rules! m { ($e:expr) => { n!($e, 0) }; }
+/// macro_rules! n { ($e:expr, $f:expr) => { f($e, $f) }; }
+/// g(m!(0))
+/// ```
+///
+/// If called with a span of the call to `f` and a context of the call to `g` this will return a
+/// span containing `m!(0)`.