def melt(orig_df: pd.DataFrame, value_columns: List[str], var_name: str, value_name: str='Cases') -> pd.DataFrame:
    'Unpivot the given DataFrame to be used with Plotly.'
    df = with_date(orig_df)
    df = df[(['Date'] + value_columns)]
    return df.melt(id_vars=['Date'], value_vars=value_columns, var_name=var_name, value_name=value_name)
Unpivot the given DataFrame to be used with Plotly.
def melt(orig_df: pd.DataFrame, value_columns: List[str], var_name: str, value_name: str='Cases') -> pd.DataFrame:
    
    df = with_date(orig_df)
    df = df[(['Date'] + value_columns)]
    return df.melt(id_vars=['Date'], value_vars=value_columns, var_name=var_name, value_name=value_name)