>
,[>,]

<[->+>+<<]> >[-<<+>>]< copy here from left cell

[[-] make loop if copied is nonzero:
 <[
  .[-] print & remove right
  <[<] move left edge
  >[.[-]] print & remove left if exist
  >[>] move right edge
 ]
 <[->+>+<<]> >[-<<+>>]< copy here from left cell
]

<[<]