def set_role role
      num = bitmask.write role
      set_ds_field(num == 1 ? false : true) # boolean field in Data store
    end
def set_role role
      num = bitmask.write role
      set_ds_field(num == 1 ? false : true) # boolean field in Data store
    end
saves the role for the role subject in the data store
 @param [Symbol] role name