<#macro m1 a b=a> ${a} ${b} <@m1 a="1"/> <#macro m2 a=b b=""> ${a} ${b} <@m2 b="2"/> <#macro m3 d b=c[a] a=d c={"3":"4"}> ${b} <@m3 d="3"/> <#attempt> <@m3 d="4"/> <#recover> m3 with d="4" Failed!