print Data instances as a nested tree; documentation

 Provides functionality similar to that of the Show class: Taking
 some arbitrary value and returning a String.
 .
  * Output is not intended to be valid Haskell
  * Requires a Data.Data.Data instance instead of a Text.Show one
  * Output, if large, is often easier to parse than `show` output
    due to the formatting as a nested tree
  * The user can adapt the behaviour at runtime using a custom
    layout expressed via syb-style extension
 .
 This package provides the documentation for a library for the Haskell
 programming language.
 See http://www.haskell.org/ for more information on Haskell.