When i use wait.keys in a block,it needs to press the keyboard twice to move on

for trial in Trials:
stim.setColor(trial[‘color’])
stim.setPos([trial[‘position’],0])

#fixation
selfx.draw()
win.flip()
core.wait(inf_time[‘cueTime’])
#stimulation
stim.draw()
win.flip()
respClock.reset()
core.wait(inf_time[‘stimTime’])
#clear screen
win.flip()
#wait for responses
keys = event.waitKeys(keyList = [‘left’,‘right’])
resp = keys[0]
rt=respClock.getTime()
if resp=='left’and trial[‘color’]==‘red’:
correct=1
elif resp=='right’and trial[‘color’]==‘green’:
correct=1
else: correct=0
win.flip()

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