code: def std(self):
      return self.aggregate("std")
  
imports: from collections import OrderedDict
  from ....serialization.serializables import BoolField, Int32Field, Int64Field, StringField
  from ....utils import pd_release_version
  from ...utils import validate_axis
  from ..core import Window
label_desc: Use image node_id 15 for calling the Expanding obj's underlying member method code with example usage: obj.std() and returns: self