tate machine. It contains the hierarchical 
  state network, and a series of methods to handle events and requests. There 
  is a basic conceptual division between elements that this state machine controls, 
  referred to as 'internal', and those outside the scope of manipulation (called 
  'external'). For example, the internal events are handled by the internal event 
  handler, <font face="Courier New, Courier, mono">ieh</font>. The external events 
  are handled by the external event handler, <font face