.replaceAll("@y", "y"));
renameArg(gem, 0, "x", "y");
renameArg(gem, 1, "z", "y_1");
SourceElement element = createFunctionDefn("y y_1", code
.replaceAll("%x", "y").replaceAll("%z", "y_1")
.replaceAll("@y", "y_2"));
assertFunctionTextEquals(gem, element);
}