class_docstr: Applies a function over a rolling window.
code: def _process(self, element, key=None):
      return element.map(self._process_layer, Element)
  
imports: import numpy
  import pandas
  import param
  from packaging.version import Version
  from ..core import Element, Operation
  from ..core.data import PandasInterface
  from ..core.util import _PANDAS_FUNC_LOOKUP, pandas_version
  from ..element import Scatter
label_desc: Use image node_id 2 for calling the rolling obj's underlying member method code with example usage: obj._process(element, key) and returns: element