fruit = ['kiwi', 'plum', 'orange', 'lemon', 'banana']
y = [ w for w in fruit if len(w)==max([ len(w) for w in fruit])][0] 
print y
banana


fruit.append("starfruit")
fruit.append("lime")
print fruit
['kiwi', 'plum', 'orange', 'lemon', 'banana', 'starfruit', 'lime']


y = [ w for w in fruit if len(w)==max([ len(w) for w in fruit])][0] 
print y
lime

# that is the wrong answer!


#the problem is that you have a for loop nested inside a for loop and they are both
# using the same variable to iterate over, so both are changing it and interfering with 
# the other. They need to be different variable names so they do not interfere. 
# Below we replace the w in the inner for loop with v. That now works. 


y = [ w for w in fruit if len(w)==max([ len(v) for v in fruit])][0] 
print y
starfruit