docs: def matches(self):
          """
          Returns a predicate for checking whether an object has a given
          set of `key:value` pairs.
          """
          def ret(obj, *args):
              if self.obj is obj:
                  return True  # avoid comparing an object to itself.
  
              for key in self.obj:
                  if self.obj[key] != obj[key]:
                      return False
  
              return True
  
          return self._wrap(ret)