"{{{{{1}}}|{{{{{2}}}}}}}" gives "{{{{{1}}}|{{{{{2}}}}}}}" [1]
"{{{{{1}}}|{{{{{2}}}}}}}"
See Help:Expansion demo templates.
Example:
{{xpdopocc|3x|#expr:2*3}} gives:
"{{3x|{{#expr:2*3}}}}" gives "666" [2]
"{{3x|{{#expr:2*3}}}}"