anchor.diff:  
       http://facebook.github.io/graphql/
       https://github.com/facebook/graphql
  -
  +  AB:10-dep19: replaced type with type_ to resolve conflict for golang generator
   */
   grammar GraphQL;
   
  
positive.code: WS
     : [ \t\n\r]+ -> skip
     ;
  
negative.code:    ;
  
  listType
     : '[' type_ ']'
     ;
  
  nonNullType
  