anchor.diff:      -..- ':'
       -..- +.typeDescription
       -..- +.(defaultValue * zeroOrOne)
  -    -- ignored
       -%> fun variable ty defaultVal ->
           {
               VariableName = variable
  
positive.code:     | StringValue of string
      | BooleanValue of bool
      | EnumValue of string
      | ListValue of ResizeArray<Value>
      | ObjectValue of IDictionary<string, Value>
  
  (**
  
  
negative.code:     {
          Alias : string option
          FieldName : string
          Arguments : Argument ListWithSource
          Directives : Directive ListWithSource
          Selections : Selection ListWithSource
      }
  and Selection =
      | FieldSelection of Field
  