input: Write a python function to create an acronym from a given sentence.
  assert create_acronym('World Health Organization') == 'WHO'
  assert create_acronym('As Soon As Possible') == 'ASAP'
  assert create_acronym('Laugh Out Loud') == 'LOL'
output: def create_acronym(sentence):
      return ''.join(word[0].upper() for word in sentence.split())