langchain/document_loaders/dataframe.py/DataFrameLoader/__init__
class DataFrameLoader:    def __init__(self, data_frame: Any, page_content_column: str = "text"):
        """Initialize with dataframe object."""
        import pandas as pd

        if not isinstance(data_frame, pd.DataFrame):
            raise ValueError(
                f"Expected data_frame to be a pd.DataFrame, got {type(data_frame)}"
            )
        self.data_frame = data_frame
        self.page_content_column = page_content_column