function(key, root, sourceText) {
	this.key = key;
	this.rootExpr = root;
	canReflect.setKeyValue(this, sourceTextSymbol, sourceText);
}
function(key, root, sourceText) {
	this.key = key;
	this.rootExpr = root;
	canReflect.setKeyValue(this, sourceTextSymbol, sourceText);
}
function ( key , root , sourceText ) { this . key = key ; this . rootExpr = root ; canReflect . setKeyValue ( this , sourceTextSymbol , sourceText ) ; }
### Lookup `new Lookup(String, [Expression])` Finds a value in the scope or a helper.
### Lookup new Lookup ( String [ Expression ] ) Finds a value in the scope or a helper .