Debug creates an Option to set the debug flag to b.

Memoize creates an Option to set the memoize flag to b.

Parse parses the data from b using filename as information in the error messages.

ParseFile parses the file identified by filename.

ParseReader parses the data from r using filename as information in the error messages.

Recover creates an Option to set the recover flag to b.

Option is a function that can set an option on the parser.