#before the loop inline script

from random import shuffle #import the shuffle function
color_bank=['red','green','blue','yellow'] #creat a list with 4 colors
shuffle(color_bank) #shuffle the list
stim_color=color_bank.pop() #take one color out to be the first stim color
next_color=color_bank.pop() #take the next one
exp.set('color',stim_color)

#after display inline
color_bank.append(stim_color)
stim_color=next_color
exp.set('color',stim_color)
shuffle(color_bank)
next_color=color_bank.pop()