code: def get_options():
      
      #already imported Qt somewhere. Use that
      loaded = loaded_api()
      if loaded is not None:
          return [loaded]
  
      mpl = sys.modules.get('matplotlib', None)
  
      if mpl is not None and not check_version(mpl.__version__, '1.0.2'):
          #1.0.1 only supports PyQt4 v1
          return [QT_API_PYQT_DEFAULT]
  
      if os.environ.get('QT_API', None) is None:
          #no ETS variable. Ask mpl, then use either
          return matplotlib_options(mpl) or [QT_API_PYQT_DEFAULT, QT_API_PYSIDE, QT_API_PYQT5]
  
      #ETS variable present. Will fallback to external.qt
      return None
docs: Return a list of acceptable QT APIs, in decreasing order of
      preference