input: Write a function to determine if a given string is a palindrome. A palindrome is a string that reads the same forward and backward. If the string is a palindrome, return True; otherwise, return False. If the string is empty, return True.
  def is_palindrome(s):
      '''This function returns True if the string s is a palindrome and False if it isn't.''' 
      return s == s[::-1]  # Checks if s is the same as its reverse.
  
  assert is_palindrome("racecar")==True
  assert is_palindrome("hello")==False
  assert is_palindrome("level")==True
  assert is_palindrome("")==True
  assert is_palindrome("a")==True
output: def is_palindrome(s):
      return s == s[::-1]