# File lib/grape_entity/exposure/base.rb, line 49
        def valid?(entity)
          is_delegatable = entity.delegator.delegatable?(@attribute) || entity.respond_to?(@attribute, true)
          if @is_safe
            is_delegatable
          else
            is_delegatable || raise(NoMethodError, "#{entity.class.name} missing attribute `#{@attribute}' on #{entity.object}")
          end
        end