input: Write a python function to sort a list of strings alphabetically.
  assert sort_strings(['abc', 'bac', 'bca', 'axy', 'axz']) == ['abc', 'axy', 'axz', 'bac', 'bca']
  assert sort_strings(['dog', 'cat', 'elephant', 'bear']) == ['bear', 'cat', 'dog', 'elephant']
  assert sort_strings(['zoo', 'apple', 'banana']) == ['apple', 'banana', 'zoo']
output: def sort_strings(strings):
      return sorted(strings)