input: def is_palindrome(input_string: str) -> bool:
      """ Check if a given string is a palindrome """
      return input_string == input_string[::-1]
  
  
  def shortest_palindrome(input_string: str) -> str:
      """ Generate the shortest palindrome starting with the input string.
      Approach:
      - Identify the longest palindromic suffix in the input string.
      - Add the reverse of the non-palindromic prefix to the end of the string.
      >>> shortest_palindrome('')
      ''
      >>> shortest_palindrome('cat')
      'catac'
      >>> shortest_palindrome('cata')
      'catac'
      """
output:     def shortest_palindrome(input_string: str) -> str:
      if not input_string:
          return ''
  
      def is_palindrome(s: str) -> bool:
          return s == s[::-1]
  
      for i in range(len(input_string)):
          if is_palindrome(input_string[i:]):
              return input_string + input_string[:i][::-1]
  
      return input_string + input_string[:-1][::-1]  # This should never be reached since the palindrome of single char is itself