js/impress.js
function( currentStep, nextStep ) {
            if ( lastEntered === currentStep ) {
                lib.util.triggerEvent( currentStep, "impress:stepleave", { next: nextStep } );
                lastEntered = null;
            }
        }
function( currentStep, nextStep ) {
            if ( lastEntered === currentStep ) {
                lib.util.triggerEvent( currentStep, "impress:stepleave", { next: nextStep } );
                lastEntered = null;
            }
        }
function ( currentStep , nextStep ) { if ( lastEntered === currentStep ) { lib . util . triggerEvent ( currentStep , "impress:stepleave" , { next : nextStep } ) ; lastEntered = null ; } }
`onStepLeave` is called whenever the currentStep element is left but the event is triggered only if the currentStep is the same as lastEntered step.
onStepLeave is called whenever the currentStep element is left but the event is triggered only if the currentStep is the same as lastEntered step .