code: function Lexer(options) {
    this.tokens = [];
    this.tokens.links = {};
    this.options = options || defaults;
    this.rules = block.normal;
  
    if (this.options.gfm) {
      if (this.options.tables) {
        this.rules = block.tables;
      } else {
        this.rules = block.gfm;
      }
    }
  }
docs: Block Lexer