def METHOD_NAME(self):
    tcl = self.interp
    tcl.setvar('a(1)',1)
    tcl.setvar('a(2)',2)
    self.assertEqual(tcl.eval('info exists a(1)'),'1')
    self.assertEqual(tcl.eval('info exists a(2)'),'1')
    tcl.unsetvar('a(1)')
    self.assertEqual(tcl.eval('info exists a(1)'),'0')
    self.assertEqual(tcl.eval('info exists a(2)'),'1')