chapter4\example4.1a.tcl
........\example4.1b.tcl
........\example4.2.tcl
........\example4.3a.tcl
........\example4.3b.tcl
........\example4.4.tcl
........\example4.5a.tcl
........\example4.5b.tcl
........\example4.6.tcl
........\subclass.tcl
chapter4