new_contents: from nex.state import GlobalState
  from nex.reader import Reader, EndOfFile
  from nex.lexer import Lexer
  from nex.instructioner import Instructioner
  from nex.banisher import Banisher
  from nex.parsing.command_parser import command_parser
  from nex.parsing.utils import ChunkGrabber
  from nex.box_writer import write_to_file
  from nex.utils import TidyEnd
  
  
  reader = Reader()
  state = GlobalState.from_defaults(font_search_paths=['/Users/ejm/projects/nex/example/fonts'])
  font_id = state.define_new_font(file_name='cmr10', at_clause=None)
  state.select_font(is_global=True, font_id=font_id)
  
  lexer = Lexer(reader, get_cat_code_func=state.codes.get_cat_code)
  instructioner = Instructioner(lexer)
  banisher = Banisher(instructioner, state, reader)
  command_grabber = ChunkGrabber(banisher, command_parser)
  
  while True:
      s = input('In: ')
      reader.insert_string(s + '\n')
      try:
          state.execute_commands(command_grabber, banisher, reader)
      except TidyEnd:
          break
  # out_path = sys.stdout.buffer
  write_to_file(state, 'done.dvi')
  
subject: Add simple REPL to test commands