demo/amd/rjs/output/unified/plain-precompiled-build.js
function lookupBlockParam(blockParamId, parts) {
	    this.useBlockParams = true;

	    this.push(['blockParams[', blockParamId[0], '][', blockParamId[1], ']']);
	    this.resolvePath('context', parts, 1);
	  }
function lookupBlockParam(blockParamId, parts) {
	    this.useBlockParams = true;

	    this.push(['blockParams[', blockParamId[0], '][', blockParamId[1], ']']);
	    this.resolvePath('context', parts, 1);
	  }
[lookupBlockParam]  On stack, before: ... On stack, after: blockParam[name], ...  Looks up the value of `parts` on the given block param and pushes it onto the stack.