input: Write a function to optimize the given Python script that reverses a string. The original script iterates through each character of the string and constructs the reversed string. The optimized version should be more efficient.
  assert reverse_string("hello")=="olleh"
  assert reverse_string("world")=="dlrow"
  assert reverse_string("python")=="nohtyp"
  assert reverse_string("algorithm")=="mhtirogla"
  assert reverse_string("")==""
output: def reverse_string(s):
      return s[::-1]