input: Write a function to optimize the given Python script that reverses a string. The optimized function should use Python slicing to reverse the string more efficiently.
  
  ### Initial Script:
  def reverse_string(string):
      reversed_string = ""
      for char in string:
          reversed_string = char + reversed_string
      return reversed_string
  
  ### Optimized Function:
  def reverse_string(string):
      return string[::-1]
  
  ### Test Cases:
  assert reverse_string("hello")=="olleh"
  assert reverse_string("Python")=="nohtyP"
  assert reverse_string("")==""
  assert reverse_string("a")=="a"
  assert reverse_string("racecar")=="racecar"
output: def reverse_string(string):
      return string[::-1]