code: def join_sentences(string1, string2, glue='.'):
      "concatenate two sentences together with punctuation glue"
      if not string1 or string1 == '':
          return string2
      if not string2 or string2 == '':
          return string1
      # both are strings, continue joining them together with the glue and whitespace
      new_string = string1.rstrip()
      if not new_string.endswith(glue):
          new_string += glue
      new_string += ' ' + string2.lstrip()
      return new_strinf join_sentences(string1, string2, glue='.'):
      "concatenate two sentences together with punctuation glue"
      if not string1 or string1 == '':
          return string2
      if not string2 or string2 == '':
          return string1
      # both are strings, continue joining them together with the glue and whitespace
      new_string = string1.rstrip()
      if not new_string.endswith(glue):
          new_string += glue
      new_string += ' ' + string2.lstrip()
      return new_string
docs: concatenate two sentences together with punctuation glue