How do you check if the words exist in the sentence in Python?

Question

So far I have got...

the_sentence = ("I love chocolate and chocolate loves me")
sentence = the_sentence.split()
print(sentence)
sentence_1 = raw_input("Enter a word")
def "word":
if word in the_sentence:
print "Yes"
elif word not in the_sentence:
print "Nope"

Thanks