input: Write a function to determine if a given string is a palindrome. 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("madam") == True
  assert is_palindrome("") == True
  assert is_palindrome("a") == True
output: def is_palindrome(s):
      return s == s[::-1]