docs: function create (id, spec) {
    validateModifiers(id, spec, ['schema', 'options'])
  
    const entity = {}
    entity.spec = spec
    entity.schema = deepFreeze(_.defaultTo(spec.schema, {}))
    entity.options = deepFreeze(_.defaultTo(spec.options, {}))
  
    validateSchema(entity.schema, entity.options)
    return entity
  }