output.htmlFor is initially empty: true
output.htmlFor always returns the same object: true
output.htmlFor after setting output.htmlFor to "a": a
for attribute value after setting output.htmlFor to "a": a
output.htmlFor after calling output.setAttribute("for", "b"): b
output.htmlFor after setting output.htmlFor to "c d": c d
for attribute value after setting output.htmlFor to "c d": c d
output.htmlFor.contains("c"): true
output.htmlFor.contains("a"): false