MemPriority tries to execute its children left to right, and returns SUCCESS
when first child returns SUCCESS. Otherwise, it returns FAILURE; When a child returns a
`RUNNING` state, its index is recorded and in the next tick the, MemPriority
calls the child recorded directly, without calling previous children again.
new MemPriority()
Methods
validators()
defines validation methods to execute at the editor; if one of them fails, a dashed red border is displayed for the node