def drop_and_index(df):
    """
    This function will take in one positional argurment:
    1.  311 df
    This function will perform the following operations to the df:
    1.  Drop category, drop report starting date, and drop report
    ending date
    2.  Set CASEID as the index
    """
    # Drop category, report starting date, and report ending date
    df.drop(columns=['Category', 
                 'Report Starting Date', 
                 'Report Ending Date' ], inplace=True)
    # Set index to case id
    df.set_index('CASEID', inplace=True)
    return df