anchor.diff:  and InlineFragment =
       {
           TypeCondition : TypeName option
  -        Directives : Directive ResizeArray
  -        Selections : Selection ResizeArray
  +        Directives : Directive ListWithSource
  +        Selections : Selection ListWithSource
       }
   
   let field selections : Parser<_, _> =
  
positive.code:         }
  
  type Operation =
      | ShorthandOperation of Selection ResizeArray
      | LonghandOperation of LonghandOperation
  
  let operation =
  
negative.code: 
  (**
  
  Both float and int parsers can be implemented to match the spec
  by way of FParsec's `numberLiteral` parser.
  
  We use some extra validation to ensure that zero does not appear before another
  