code: def add_params(self, **kw):
          
          for k, v in kw.items():
              if k not in self.params:
                  raise ValidationError(
                      '"%s" is not a valid parameter for %s'
                      % (k, self.__class__.__name__))
              self.params[k].validate(v)
  
          self._orig_kwargs.update(kw)
          self.kwargs = self._orig_kwargs.copy()
docs: Add [possibly many] parameters to the Assembly.
  
          Parameters will be checked against known UCSC parameters and their
          supported formats.