A pyramid model returned by one of the create methods of
advanced.patterns.facePatterns.pyramidSimple.
Which face of the model to read, counted from 0 in the order the faces were given.
The V index of the row, counted from 0; an index with no cells gives an empty list.
A pyramid model, one of its faces and a V index, for
advanced.patterns.facePatterns.pyramidSimple.getAllPyramidUCellsOnFaceAtV, which returns the row of cells at that V index.