flag_is_rush() flags whether a shot attempt is a rush attempt, defined as any shot attempt occurring within 4 seconds of a prior event in the neutral or defensive zone with no stoppage in play in between.
flag_is_rush(play_by_play)data.frame with one row per event (play) and added isRush column
data.frame of play-by-play(s); see gc_play_by_play() and/or wsc_play_by_play() for reference