def klass
      klass_name = options.fetch(:class, name).to_s.camelize
      Object.const_get(klass_name)
    rescue NameError
      raise InvalidClassError, "class #{klass_name.inspect} does not exist"
    end
def klass
      klass_name = options.fetch(:class, name).to_s.camelize
      Object.const_get(klass_name)
    rescue NameError
      raise InvalidClassError, "class #{klass_name.inspect} does not exist"
    end
@return [Class]

 @raise [InvalidClassError]