result = (
    pd.read_csv("sales.csv")  # Start with raw data
    
    .assign(
        # Create revenue column
        revenue=lambda df: df["quantity"] * df["price"],
        
        # Extract month from order_date
        month=lambda df: pd.to_datetime(df["order_date"]).dt.to_period("M")
    )
    
    # Filter for recent orders
    .loc[lambda df: df["order_date"] >= "2023-01-01"]
    
    # Group and aggregate
    .groupby(["category", "month"])["revenue"]
    .sum()
    
    # Convert to DataFrame
    .reset_index()
    
    # Sort results
    .sort_values(by="revenue", ascending=False)
)