All functions have to be called according to the ESI standard, using colons, e.g. lib:FUNCTIONNAME(params)
STATE:ON_ENTER callback of the STATE helper class
This callback is called, whenever a state is entered.
STATE:ON_LEAVE callback of the STATE helper class
This callback is called, whenever a state is leafed.
this function is evaluated in order to decide if a state transition is possible.
TRANSITION:ON_TRANSITION callback of the Transtion helper class
This callback is called, whenever a Transition is executed.
PREPARE callback e.g. for input procesing
default implementation setting runTime and triggerTime to now If this callback should be overwritte with each instance of the esi-state-machine class. at least runTime and triggerTime must be set. no input parameters, inputs shall be read during the prepare phase.