nodes: 0, module; 1, function_definition; 2, function_name:getMd5Checksum; 3, parameters; 4, block; 5, identifier:self; 6, expression_statement; 7, expression_statement; 8, expression_statement; 9, expression_statement; 10, return_statement; 11, comment:"""
          Returns the MD5 checksum for this reference set. This checksum is
          calculated by making a list of `Reference.md5checksum` for all
          `Reference`s in this set. We then sort this list, and take the
          MD5 hash of all the strings concatenated together.
          """; 12, assignment; 13, assignment; 14, assignment; 15, identifier:md5checksum; 16, identifier:references; 17, call; 18, identifier:checksums; 19, call; 20, identifier:md5checksum; 21, call; 22, identifier:sorted; 23, argument_list; 24, attribute; 25, argument_list; 26, attribute; 27, argument_list; 28, call; 29, keyword_argument; 30, string; 31, identifier:join; 32, list_comprehension; 33, call; 34, identifier:hexdigest; 35, attribute; 36, argument_list; 37, identifier:key; 38, lambda; 39, call; 40, for_in_clause; 41, attribute; 42, argument_list; 43, identifier:self; 44, identifier:getReferences; 45, lambda_parameters; 46, call; 47, attribute; 48, argument_list; 49, identifier:ref; 50, identifier:references; 51, identifier:hashlib; 52, identifier:md5; 53, identifier:checksums; 54, identifier:ref; 55, attribute; 56, argument_list; 57, identifier:ref; 58, identifier:getMd5Checksum; 59, identifier:ref; 60, identifier:getMd5Checksum
code: def getMd5Checksum(self):
          """
          Returns the MD5 checksum for this reference set. This checksum is
          calculated by making a list of `Reference.md5checksum` for all
          `Reference`s in this set. We then sort this list, and take the
          MD5 hash of all the strings concatenated together.
          """
          references = sorted(
              self.getReferences(),
              key=lambda ref: ref.getMd5Checksum())
          checksums = ''.join([ref.getMd5Checksum() for ref in references])
          md5checksum = hashlib.md5(checksums).hexdigest()
          return md5checksum