def set_roles *roles
      raise ArgumentError, "A single role strategy can only allow setting a single role, was: #{roles}" if (roles.size > 1)
      set_role roles.flat_uniq.first
    end
def set_roles *roles
      raise ArgumentError, "A single role strategy can only allow setting a single role, was: #{roles}" if (roles.size > 1)
      set_role roles.flat_uniq.first
    end
saves the role for the user in the data store