code: def _seen(self):
      seen = set(self._markers)
      if self.parent is not None:
          seen.update(self.parent.keywords)
      return seen
  
imports: import inspect
  import warnings
  from collections import namedtuple
  from operator import attrgetter
  import attr
  import six
  from ..compat import ascii_escaped
  from ..compat import ATTRS_EQ_FIELD
  from ..compat import getfslineno
  from ..compat import MappingMixin
  from ..compat import NOTSET
  from _pytest.deprecated import PYTEST_PARAM_UNKNOWN_KWARGS
  from _pytest.outcomes import fail
  from _pytest.warning_types import PytestUnknownMarkWarning
label_desc: Use image node_id 6 for calling the NodeKeywords obj's underlying member method code with example usage: obj._seen() and returns: seen