func_unit.position(position, callback) -> String|funcUnit
{optional:Object|Function}
If provided uses this as a check before continuing to the next action. Or you can provide a function that returns true to continue to the next action.
{optional:Function}
a callback that will run after this action completes.
{String|funcUnit}
if the position parameter is provided, returns the funcUnit selector for chaining, otherwise returns the offset of the selector.
Gets an element's position or waits until the position is a specified value.