class_docstr: Preprocessor to convert notebooks to Python source to strips out all
  magics. To be applied after the preprocessors that can handle
  holoviews magics appropriately.
code: def preprocess_cell(self, cell, resources, index):
      if cell["cell_type"] == "code":
          cell["source"] = strip_magics(cell["source"])
      return cell, resources
  
imports: import ast
  from nbconvert.preprocessors import Preprocessor
label_desc: Use image node_id 1 for calling the StripMagicsProcessor obj's underlying member method code with example usage: obj.preprocess_cell(cell, resources, index) and returns: cell,  resources