<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def find(model, rid):
 """ Find a model from the store by resource id """


    validate_rid(model, rid)

    rid_field = model.rid_field
    model = goldman.sess.store.find(model.RTYPE, rid_field, rid)

    if not model:
        abort(exceptions.DocumentNotFound)

    return model