langchain/document_loaders/facebook_chat.py/concatenate_rows
def concatenate_rows(row: dict) -> str:
    """Combine message information in a readable format ready to be used."""
    sender = row["sender_name"]
    text = row["content"]
    date = datetime.datetime.fromtimestamp(row["timestamp_ms"] / 1000).strftime(
        "%Y-%m-%d %H:%M:%S"
    )
    return f"{sender} on {date}: {text}\n\n"