anchor.diff:      %i + (%j - %k)
     @>
   
  +let assocSubAddIndex_exp = 
  +  <@
  +    (%i - %j) + %k
  +    <==>
  +    %i - (%j - %k)
  +  @>
  +
  +let assocSubSubIndex_exp = 
  +  <@
  +    (%i - %j) - %k
  +    <==>
  +    %i - (%j + %k)
  +  @>
  +
   let subSameIndex_exp = 
     <@
       %i - %i
  
positive.code:     %a - (%b + %c)
    @>
  
  let vectorBuildGet_exp = 
    <@
      (vectorBuild %k %FIN).[%i]
  
negative.code: let constFold0Index_exp = 
    <@ 
      %i + 0
      <==>
      %i
    @>
  
  let constFoldN0Index_exp = 
    <@ 
      %i - 0
      <==>
      %i
    @>
  