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