<s> try : <EOL> import ast <EOL> from pip . _vendor . _markerlib . markers import default_environment , compile , interpret <EOL> except ImportError : <EOL> if '<STR_LIT>' in globals ( ) : <EOL> raise <EOL> def default_environment ( ) : <EOL> return { } <EOL> def compile ( marker ) : <EOL> def marker_fn ( environment = None , override = None ) : <EOL> return not marker . strip ( ) <EOL> marker_fn . __doc__ = marker <EOL> return marker_fn <EOL> def interpret ( marker , environment = None , override = None ) : <EOL> return compile ( marker ) ( ) </s>
