code: def loaded_api():
      
      if 'PyQt4.QtCore' in sys.modules:
          if qtapi_version() == 2:
              return QT_API_PYQT
          else:
              return QT_API_PYQTv1
      elif 'PySide.QtCore' in sys.modules:
          return QT_API_PYSIDE
      elif 'PyQt5.QtCore' in sys.modules:
          return QT_API_PYQT5
      return None
docs: Return which API is loaded, if any
  
      If this returns anything besides None,
      importing any other Qt binding is unsafe.
  
      Returns
      -------
      None, 'pyside', 'pyqt', or 'pyqtv1'