def by_site_id(self,site_id: str) -> SiteItemRequestBuilder:
        """
        Provides operations to manage the sites property of the microsoft.graph.group entity.
        param site_id: The unique identifier of site
        Returns: SiteItemRequestBuilder
        """
        if site_id is None:
            raise TypeError("site_id cannot be null.")
        from .item.site_item_request_builder import SiteItemRequestBuilder

        url_tpl_params = get_path_parameters(self.path_parameters)
        url_tpl_params["site%2Did"] = site_id
        return SiteItemRequestBuilder(self.request_adapter, url_tpl_params)

        Provides operations to manage the sites property of the microsoft.graph.group entity.
        param site_id: The unique identifier of site
        Returns: SiteItemRequestBuilder
        
msgraph/generated/groups/item/sites/sites_request_builder.py