code: def contains(self, *items):
          
          if len(items) == 0:
              raise ValueError('one or more args must be given')
          elif len(items) == 1:
              if items[0] not in self.val:
                  if self._check_dict_like(self.val, return_as_bool=True):
                      self._err('Expected <%s> to contain key <%s>, but did not.' % (self.val, items[0]))
                  else:
                      self._err('Expected <%s> to contain item <%s>, but did not.' % (self.val, items[0]))
          else:
              missing = []
              for i in items:
                  if i not in self.val:
                      missing.append(i)
              if missing:
                  if self._check_dict_like(self.val, return_as_bool=True):
                      self._err('Expected <%s> to contain keys %s, but did not contain key%s %s.' % (self.val, self._fmt_items(items), '' if len(missing) == 0 else 's', self._fmt_items(missing)))
                  else:
                      self._err('Expected <%s> to contain items %s, but did not contain %s.' % (self.val, self._fmt_items(items), self._fmt_items(missing)))
          return self
docs: Asserts that val contains the given item or items.