message: Review and update tutorial step 3B.
  Part of
diff: @@ -21,7 +21,7 @@ This can be accomplished using two features of the Parsing DSL:
  * [CONSUME](http://sap.github.io/chevrotain/documentation/0_27_3/classes/_chevrotain_d_.parser.html#consume1) will return
  The [Token](http://sap.github.io/chevrotain/documentation/0_27_3/classes/_chevrotain_d_.token.html) instance consumed.
  * [SUBRULE](http://sap.github.io/chevrotain/documentation/0_27_3/classes/_chevrotain_d_.parser.html#subrule1) will return
  - the result on invoking the subrule.
  + the result of the grammar rule invoked.
  ### A simple contrived example:
  @@ -57,7 +57,7 @@ and the **topRule** adds it to the final result.
  #### Back To the mini SQL Select grammar:
  -For this parser lets build a more complex data structure instead of simply returning a number.
  +For this grammar lets build a more complex data structure (an AST) instead of simply returning a number.
  Our selectStatement rule will now return an object with four properties:
  ```javascript
  @@ -74,6 +74,7 @@ $.RULE("selectStatement", () => {
  type : "SELECT_STMT",
  selectClause : select,
  fromClause : from,
  + // may be undefined if the OPTION was not entered.
  whereClause : where
  }
  })
  @@ -82,10 +83,9 @@ $.RULE("selectStatement", () => {
  Three of those properties (selectClause / fromClause / whereClause) are the results of invoking
  other parser rules.
  -Lets look at one of those sub rules:
  +Lets look at the "selectClause" rule implemntaiton:
  ```javascript
  -
  $.RULE("selectClause", () => {
  let columns = []
  