anchor.diff:    {( 0 1 "" "1" "x" "[]" () (1) (() ()) ) | add 0}
       [0,1,0,1,0,0,0,0,0]
   
  -  {( 0 1 "" "1" "x" "[]" () (1) (() ()) ) | map block "{__ | then 1 else 0}"}
  +  {( 0 1 "" "1" "x" "[]" () (1) (() ()) ) | map block "{__ | if __ then 1 else 0}"}
       [0,1,0,1,1,1,0,1,1]
     
     {( 0 1 "" "1" "x" "[]" () (1) (() ()) ) | map block "{__ | string lowercase}"}
  
positive.code:     Tail position pipeline vars flake out [probably requires placeholder segtype]
        {2 | >two | "" | _two}
          2
  
negative.code: 
      {1 | else "{fff fff}" | add 1}
        2
  
      {if :true then :awesome}
        awesome
  