ModuleNotFoundError: No module named 'transformers.modeling_roberta'

im trying to use longformer and in its code it has from transformers.modeling_roberta import RobertaConfig, RobertaModel, RobertaForMaskedLM
but although I install the transformers and I can do import transformers I still get an error when I do:
from transformers.modeling_roberta import RobertaConfig, RobertaModel, RobertaForMaskedLM
any suggestion on how to install it? or what to do?

You should import those objects from transformers directly.

Im not able to do it, does it mean I have not install some of the parts correctly?