langchain/document_loaders/notebook.py/NotebookLoader/load
class NotebookLoader:    def load(
        self,
    ) -> List[Document]:
        """Load documents."""
        try:
            import pandas as pd
        except ImportError:
            raise ImportError(
                "pandas is needed for Notebook Loader, "
                "please install with `pip install pandas`"
            )
        p = Path(self.file_path)

        with open(p, encoding="utf8") as f:
            d = json.load(f)

        data = pd.json_normalize(d["cells"])
        filtered_data = data[["cell_type", "source", "outputs"]]
        if self.remove_newline:
            filtered_data = filtered_data.applymap(remove_newlines)

        text = filtered_data.apply(
            lambda x: concatenate_cells(
                x, self.include_outputs, self.max_output_length, self.traceback
            ),
            axis=1,
        ).str.cat(sep=" ")

        metadata = {"source": str(p)}

        return [Document(page_content=text, metadata=metadata)]