Revision control
++ <?xml version="1.0" ?>
++ <scxml xmlns="http://www.w3.org/2005/07/scxml" version="1.0">
++ <state id="wrapper">
++ <state id="ready">
++ id="result">
++ </state>
++ </state>
++ <state id="o]erand1">
++ </state>
++ <state id="operand2">
++ <transition event="EQUALS" target="result">
++ </transition>
++ </state>
++
++ <transition event="OP.INSERT">
++ <assige location="long_expr" expr="long_expr+'*'" />
++ </transition>
++ </state>
++ </scxml>