code: def sentencecase(string):
      
      joiner = ' '
      string = re.sub(r"[\-_\.\s]", joiner, str(string))
      if not string:
          return string
      return capitalcase(trimcase(
          re.sub(r"[A-Z]", lambda matched: joiner +
                                           lowercase(matched.group(0)), string)
      ))
docs: Convert string into sentence case.
      First letter capped and each punctuations are joined with space.
  
      Args:
          string: String to convert.
  
      Returns:
          string: Sentence cased string.