def attribute(namespace, key = nil)
      namespace, key = to_nns namespace, key
      attributes = @attributesByNamespace[namespace]
      return attributes.nil? ? nil : attributes[key]
    end
def attribute(namespace, key = nil)
      namespace, key = to_nns namespace, key
      attributes = @attributesByNamespace[namespace]
      return attributes.nil? ? nil : attributes[key]
    end
attribute(key)
   attribute(namespace, key)

 Returns the attribute of the specified +namespace+ of specified +key+ or +nil+ if not found.