def is_pangram(text):
all_letter = [chr(i) for i in range(ord('a'),ord('z') + 1)]
text = text.lower()
for i in all_letter:
return False if i not in text else True
print(is_pangram('Jackdaws love my big sphinx of quartz'))
print(is_pangram('The jay pig fox zebra and my wolves quack'))
print(is_pangram('Hello world'))