Why [None] does appear in output?

Question

def my_islower(word):
alphbet = 'qwertyuioplkjhgfdsazxcvbnm'
if word in alphbet:
print (True)
else:
print (False)

lowers =list(map(my_islower,"ali"))
print (lowers)

Answer 1

Well because function my_islower(word) is returning nothing.