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