Specifies the GScanner parser configuration. Most settings can be changed during the parsing phase and will affect the lexical parsing of the next unpeeked token.
specifies the characters at the start and end of single-line comments. The default is "#\n" which means that single-line comments start with a '#' and continue until a '\n' (end of line).
specifies which characters should be skipped by the scanner (the default is the whitespace characters: space, tab, carriage-return and line-feed).