An apparent change in the direction of the poem, caused by a change in the observational position of the reader. 
Like a virus moving inside your skull. 
What you want is that, present or absent, [I]ts status is certain. 
This online application automatically generates rule-abiding nonlinear readings of Ex Machina, as originally written by Jonathan Ball, whose first print edition was published by Book*Hug in 02009.
This literary stress-test assists in performing a qualitative analysis under the following hypothesis: nonlinear constructions of Ex Machina are semantically and poetically inferior to the first published linear construction. The methodology is adjustable due to lack of instruction in the original text, but the current simulation available is limited due to media porting instability. (In this case, a textuality deficiency with regards to physical media from the text's self-referential nature of itself being a printed and bounded book.)
The equivalent null-hypothesis would therefore state that rule-abiding nonlinear structures would make an equal or greater amount of sense as a linear reading of the original manuscript.
The methodology for this experiment uses an improvisation upon Edsger Dijkstra's graph-based pathfinding algorithm, unweighted. It accepts two parameters before running: starting location and desired ending location. It will then search for the shortest possible path between these two subsets. (Some possible sets of the same shortest length with different contents may exist.)