def method_missing(key_name, *args, &block)
      if @_scope.respond_to?(key_name) && !ignore_scope_methods.include?(key_name)
        @_scope.send(key_name, *args, &block)
      else
        key(key_name, *args, &block)
      end
    end
def method_missing(key_name, *args, &block)
      if @_scope.respond_to?(key_name) && !ignore_scope_methods.include?(key_name)
        @_scope.send(key_name, *args, &block)
      else
        key(key_name, *args, &block)
      end
    end
Public: Called anytime the compiler is passed JSON keys,
 first checks to see if the parent object contains the method like
 a Rails helper.

 key_name - The key for the JSON member.
 args     - An array of values passed to JSONBuilder::Value.
 block    - Yielding any block passed to the element.

 Returns nothing.