Invalid value "flip" 

Valid values are:

 opt_kind
 expiration
 description
 trading_hours
 multiplier
 product
 mmy
 last_trade
 underlying
 strike
 g_time
 theo
 volatility
 delta
 gamma
 theta
 rho
 vega
 event_time
 day_id
 day_open_price
 day_high_price
 day_low_price
 day_close_price
 day_close_price_type
 prev_day_id
 prev_day_close_price
 prev_day_close_price_type
 prev_day_volume
 oi
 oi_ch
 halt_start_time
 halt_end_time
 high_limit_price
 low_limit_price
 high_52_week_price
 low_52_week_price
 bid_time
 bid_exchange_code
 bid_price
 bid_size
 ask_time
 ask_exchange_code
 ask_price
 ask_size
 t_time
 sequence
 exchange_code
 price
 change
 size
 t_day_id
 day_volume
 day_turnover
 tick_direction
 extended_trading_hours
 spread
 value
 volm
 deltas
 gammas
 vegas
 thetas
 rhos
 value_buy
 volm_buy
 deltas_buy
 gammas_buy
 vegas_buy
 thetas_buy
 rhos_buy
 value_sell
 volm_sell
 deltas_sell
 gammas_sell
 vegas_sell
 thetas_sell
 rhos_sell
 value_und
 volm_und
 deltas_und
 gammas_und
 vegas_und
 thetas_und
 rhos_und
 value_bs
 volm_bs
 expiration_ts
 vanna
 vomma
 charm
 dxoi
 gxoi
 vxoi
 txoi
 vannaxoi
 vommaxoi
 charmxoi
 gxvolm
 vxvolm
 txvolm
 vannaxvolm
 vommaxvolm
 charmxvolm
 dxvolm
 volm_5m
 value_5m
 volmbs_5m
 valuebs_5m
 volm_15m
 value_15m
 volmbs_15m
 valuebs_15m
 volm_30m
 value_30m
 volmbs_30m
 valuebs_30m
 volm_60m
 value_60m
 volmbs_60m
 valuebs_60m