lazy evaluation of blocks in a groovy string

gistfile1.groovy

def lazy = { {w->w<<it()}.asWritable() }

def x = "it is now ${System.currentTimeMillis()}"
def y = "it is now ${{it->it<<System.currentTimeMillis()}.asWritable()}"
def z = "it is now ${lazy{System.currentTimeMillis()}}"

// change to x,y,z - x prints the same number all 5 times
(1..5).each { println z; sleep 250 }