At a busy road in front of a gate of Bishan Middle School, the crosswalk is installed to keep the students safe when they cross the road after school.

Let's say you meet a day-older version of yourself just before you cross through the front of the gate and jump backward in time, as if you will hang around for a day to greet yourself in the past.

This split is represented by a diamond (a gate element or gateway in BPMN terminology) with a cross inside it.