We don't directly support printing these.
To prevent future issues being raised about the pattern being missing if
someone tries to print one, hide everything.
The `original_pattern` introduced a tenuous dependency to the expression
value as a whole, and after some consideration, I decided that it would
be better for the developer to manage their own pattern strings.
In the event you need to print the text representation of a pattern,
it's usually better that you manage the memory of it as well.
Feoramund