code: def current_boost_dir():
      
      # Path to directory containing this script.
      path = os.path.dirname( os.path.realpath(__file__) )
      # Making sure it is located in "${boost-dir}/libs/mpl/preprocessed".
      for directory in reversed( ["libs", "mpl", "preprocessed"] ):
          (head, tail) = os.path.split(path)
          if tail == directory:
              path = head
          else:
              return None
      return os.path.relpath( path )
docs: Returns the (relative) path to the Boost source-directory this file is located in (if any).