nl_tokens: Parse a given uncssrc file .
pl_tokens: function parseUncssrc ( filename ) { let options = JSON . parse ( fs . readFileSync ( filename , 'utf-8' ) ) ; /* RegExps can't be stored as JSON, therefore we need to parse them manually.
       * A string is a RegExp if it starts with '/', since that wouldn't be a valid CSS selector.
       */ options . ignore = options . ignore ? options . ignore . map ( strToRegExp ) : undefined ; options . ignoreSheets = options . ignoreSheets ? options . ignoreSheets . <mask> ( strToRegExp ) : undefined ; return options ; }