Module pat 
Source - CommaRecoveryMode
- Whether or not to recover a a, bwhen parsing patterns as(a, b)or that anda | b.
- EatOrResult ๐ 
- The result of eat_or_separator. We want to distinguish which case we are in to avoid
emitting duplicate diagnostics.
- Expected
- PatternLocation
- The syntax location of a given pattern. Used for diagnostics.
- RecoverColon
- Whether or not to recover a :when parsing patterns that were meant to be paths.
- RecoverComma
- Whether or not to recover a ,when parsing or-patterns.
- WHILE_PARSING_OR_MSG ๐