
  $ cat > ppx-string.ml << "EOF"
  > let s = {|
  > |}
  > 
  > let s = {xx|
  > xx|}
  > 
  > let s =
  >   {xx|
  > |}
  > |xx}
  > 
  > let s = {| foo
  > bar
  > |}
  > 
  > let s = {| foo
  >     bar
  > |}
  > 
  > let s = {| foo
  > bar
  >    |}
  > 
  > let s =
  >   {|
  > |}
  > 
  > let s =
  >   {|
  >   |}
  > 
  > let s =
  >   {| foo
  > |}
  > 
  > let s =
  >   {xx| foo
  >   bar
  >         |yy}
  > baz
  > |xx}
  > 
  > let s =
  >   {|
  > foo bar
  >     baz
  >        |}
  > EOF

  $ ocp-indent ppx-string.ml
  let s = {|
  |}
  
  let s = {xx|
  xx|}
  
  let s =
    {xx|
  |}
  |xx}
  
  let s = {| foo
  bar
  |}
  
  let s = {| foo
      bar
  |}
  
  let s = {| foo
  bar
     |}
  
  let s =
    {|
  |}
  
  let s =
    {|
    |}
  
  let s =
    {| foo
  |}
  
  let s =
    {xx| foo
    bar
          |yy}
  baz
  |xx}
  
  let s =
    {|
  foo bar
      baz
         |}
