Groovy: command chain with dots and multiple assignments

Question

I'm trying to understand why command chaining without dots is not working with multiple assignments. For example this dummy code:

def (one, two) = String.valueOf 12 trim() iterator()

Raises:

Script1.groovy: 2: expecting EOF, found '12' @ line 2, column 33. def (one, two) = String.valueOf 12 trim() iterator()

Of course if I add the dot then everything is fine