input: Write a function to capitalize all strings in a list.
  assert capitalize_strings(['hello', 'world', 'python']) == ['HELLO', 'WORLD', 'PYTHON']
  assert capitalize_strings(['test', 'case', 'example']) == ['TEST', 'CASE', 'EXAMPLE']
  assert capitalize_strings(['apple', 'banana', 'cherry']) == ['APPLE', 'BANANA', 'CHERRY']
output: def capitalize_strings(lst):
      return [s.upper() for s in lst]