def __init__(self, **kwargs):
super().__init__(**kwargs)<EOL>if docker is None:<EOL><INDENT>raise ArcaMisconfigured(ArcaMisconfigured.PACKAGE_MISSING.format("<STR_LIT>"))<EOL><DEDENT>self._containers = set()<EOL>self.client = None<EOL>self.alpine_inherited = None<EOL>
Initializes the instance and checks that the docker package is installed.