code: def is_installed():
    # type: () -> bool
    
    try:
      # noinspection PyUnresolvedReferences
      from ccurl import Curl as CCurl
    except ImportError:
      return False
    else:
      # noinspection PyUnresolvedReferences
      from iota.crypto import Curl
      return issubclass(Curl, CCurl)
docs: Returns whether the C extension is installed correctly.