what is the issue with object accessability

HI,
I did small library for suapui,
and I am using that in my tests...
But I can not understand the issue with object accessability in script functions...
Can you answer, pls

Ok let me articulate a question:
why my object (xxx) is not visible in the functions, and the (tc) object is visible?

my script (test step = script) in given soapui testcase looks like this:
=========================================================
import my.lib.blabla.* //here is MyLibClass
def tc=TestRunner.TestCase


def xxx = new MyLibClass(1)

def out = my_function(1,2)

log.info out

return

def my_function(a,b) {

def str1 = xxx.method1(a)
def str2 = xxx.method2(b)
def str3 = tc.getClass().getName()

return str3 + " : " + str2 + " : " + str1
}
===================================

as you can see I am trying to access xxx object in my_function(a,b)
why I receive error here:
:ERROR:An error occured [No such property: xxx for class: Script21], see error log for details