code: def surround_previous_word(input_str):
      '''
      Surround last word in string with parentheses. If last non-whitespace character
      is delimiter, do nothing
      '''
      start = None
      end = None
      for i, char in enumerate(reversed(input_str)):
          if start is None:
              if char in '{}()[]<>?|':
                  return input_str
              elif char != ' ':
                  start = i
          else:
              if char in '{}()[]<>?| ':
                  end = i
                  break
      if start is None:
          return input_str
      if end is None:
          end = len(input_str)
      new_str = ''
      for i, char in enumerate(reversed(input_str)):
          if char == ' ' and i + 1 == start:
              continue
          if i == start:
              new_str += ') '
          elif i == end:
              new_str += '('
          new_str += char
      if end == len(input_str):
          new_str += '('
      return new_str[::-1f surround_previous_word(input_str):
      '''
      Surround last word in string with parentheses. If last non-whitespace character
      is delimiter, do nothing
      '''
      start = None
      end = None
      for i, char in enumerate(reversed(input_str)):
          if start is None:
              if char in '{}()[]<>?|':
                  return input_str
              elif char != ' ':
                  start = i
          else:
              if char in '{}()[]<>?| ':
                  end = i
                  break
      if start is None:
          return input_str
      if end is None:
          end = len(input_str)
      new_str = ''
      for i, char in enumerate(reversed(input_str)):
          if char == ' ' and i + 1 == start:
              continue
          if i == start:
              new_str += ') '
          elif i == end:
              new_str += '('
          new_str += char
      if end == len(input_str):
          new_str += '('
      return new_str[::-1]
docs: Surround last word in string with parentheses. If last non-whitespace character
      is delimiter, do nothing