code: def pretty_print(ast, indent_str='  '):
      
  
      return ''.join(chunk.text for chunk in pretty_printer(indent_str)(ast))
docs: Simple pretty print function; returns a string rendering of an input
      AST of an ES5 Program.
  
      arguments
  
      ast
          The AST to pretty print
      indent_str
          The string used for indentations.  Defaults to two spaces.