class_docstr: Mixin class for Cartesian 2D elements to add basic support for
  SelectionExpr streams.
class_docstr_tok: ["Mixin","class","for","Cartesian","2D","elements","to","add","basic","support","for","SelectionExpr","streams","."]
code: def _skip(self, **kwargs):
      skip = kwargs.get("index_cols") and self._index_skip
      if skip:
          self._index_skip = False
      return skip
  
imports: import sys
  import numpy
  import pandas
  from ..core import Dataset, NdOverlay, util
  from ..streams import Lasso, Selection1D, SelectionXY
  from ..util.transform import dim
  from .annotation import HSpan, VSpan
label_desc: Use image node_id 7 for calling the Selection2DExpr obj's underlying member method code with example usage: obj._skip() and returns: skip