def becomes!(klass)
      became = becomes(klass)
      sti_type = nil
      if !klass.descends_from_active_record?
        sti_type = klass.sti_name
      end
      became.public_send("#{klass.inheritance_column}=", sti_type)
      became
    end
def becomes!(klass)
      became = becomes(klass)
      sti_type = nil
      if !klass.descends_from_active_record?
        sti_type = klass.sti_name
      end
      became.public_send("#{klass.inheritance_column}=", sti_type)
      became
    end
Wrapper around #becomes that also changes the instance's sti column value.
 This is especially useful if you want to persist the changed class in your
 database.

 Note: The old instance's sti column value will be changed too, as both objects
 share the same set of attributes.