Since these two are only used in Message#parse_message, and you recommend extracting out that whole Regexp, maybe I should not dismantle it in the first place, in `message.rb`:

```ruby
HEADER_SEPARATOR = /#{CRLF}#{CRLF}|#{CRLF}#{WSP}*#{CRLF}(?!#{WSP})/m

def parse_message
  header_part, body_part = raw_source.lstrip.split(HEADER_SEPARATOR, 2)
```