input: Write a function that optimizes a given Python script that reverses a string. The optimized function should use Python's slice operator to reverse the string in a more efficient manner than the provided loop-based approach.
  
  def reverse_string(string):
      return string[::-1]
  
  assert reverse_string("hello")=="olleh"
  assert reverse_string("Python")=="nohtyP"
  assert reverse_string("")==""
output: def reverse_string(string):
      return string[::-1]