While you can define a matcher in-line in the example like this, I recommend putting it in the example group (e.g. in a `describe` or `context` block).  As this exists now, someone could write another example that uses this matcher and that would pass if it ran after this one but fail if it ran before.  I like to avoid ordering dependencies so putting it in the example group describe or context block defines it when the file is loaded and removes the ordering from the equation.