docs: function() {
                  var compareOps = ['==', '!=', '<', '>', '<=', '>='];
                  var expr = this.parseAdd();
                  var ops = [];
  
                  while (1) {
                      var tok = this.nextToken();
  
                      if (!tok) {
                          break;
                      } else if (lib.indexOf(compareOps, tok.value) !== -1) {
                          ops.push(new nodes.CompareOperand(tok.lineno,
                              tok.colno,
                              this.parseAdd(),
                              tok.value));
                      } else {
                          this.pushToken(tok);
                          break;
                      }
                  }
  
                  if (ops.length) {
                      return new nodes.Compare(ops[0].lineno,
                          ops[0].colno,
                          expr,
                          ops);
                  } else {
                      return expr;
                  }
              }