code: def clear(self, domain=None, path=None, name=None):
          
          if name is not None:
              if (domain is None) or (path is None):
                  raise ValueError(
                      "domain and path must be given to remove a cookie by name")
              del self._cookies[domain][path][name]
          elif path is not None:
              if domain is None:
                  raise ValueError(
                      "domain must be given to remove cookies by path")
              del self._cookies[domain][path]
          elif domain is not None:
              del self._cookies[domain]
          else:
              self._cookies = {}
docs: Clear some cookies.
  
          Invoking this method without arguments will clear all cookies.  If
          given a single argument, only cookies belonging to that domain will be
          removed.  If given two arguments, cookies belonging to the specified
          path within that domain are removed.  If given three arguments, then
          the cookie with the specified name, path and domain is removed.
  
          Raises KeyError if no matching cookie exists.