ngDirectiveDefinition'      ::[DirectiveDefinitionConf] -> DirectiveDefinition -> Fay DirectiveDefinition
ngDirectiveDefinition' []                 d = return d
ngDirectiveDefinition'      ::[DirectiveDefinitionConf] -> DirectiveDefinition -> Fay DirectiveDefinition
ngDirectiveDefinition' []                 d = return d
ngDirectiveDefinition' []                 d = return d