Generate implicit event when state becomes active
enter( generates an implicit
local event when the chart execution enters the state state_name)state_name.
If more than one state has the same name, use dot notation to specify the name of
the state. For more information, see Identify Data by Using Dot Notation.
en( is an alternative way to
execute state_name)enter(state_name).
The enter operator is supported only in Stateflow® charts in Simulink® models.