code: def contains_sequence(self, *items):
          
          if len(items) == 0:
              raise ValueError('one or more args must be given')
          else:
              try:
                  for i in xrange(len(self.val) - len(items) + 1):
                      for j in xrange(len(items)):
                          if self.val[i+j] != items[j]:
                              break
                      else:
                          return self
              except TypeError:
                  raise TypeError('val is not iterable')
          self._err('Expected <%s> to contain sequence %s, but did not.' % (self.val, self._fmt_items(items)))
docs: Asserts that val contains the given sequence of items in order.