edge rounded OpenSCAD cube

Needing to add some OpenSCAD 'cubes' to a design with different edges radiused to different radii I sidetracked myself into building a reuseable module to radius any number of edges of a cube each to any radius of choice. The module edgeroundcube.scad exists in two formats the main one is verbose and includes full descriptions of use and function. If you like to keep files small there is also erct.scad (edge rounded cube tokenised) which has had all comments and whitespace removed but still functions identically. There's not much use for an edge rounded cube per-se (except for making dice) but as a component of something complex this can be called with two twelve-element vectors and the call edgeround(x,y,z,vector1,vector2);. Both copies of the module have a test routine which can be uncommented to build a fully radiused 'bar of soap' model.
Models pictured are

1. a cube with a single radiused edge.
2. a block with all vertical edges radiused.
3. a 'smartphone' shape clearly showing the tricuspid artifact at each corner where radii on meeting edges are not the same.
4. A fettled block with very small edge radiuses which, because they are all the same radius allows for very clean corners
   and 5) a 'bar of soap' where all edges are radiused larger and the same allowing again for fully eighth-spherical corners.
   Be aware that due to the large number of subtractions made during the build there are often unwanted and invisible artifacts. All models should be tested for mesh accuracy and fixed before attempting to slice.
   erc1.stl has 8 degenerate facets
   erc2.stl has 8 degenerate facets
   erc3.stl has 14 degenerate facets
   erc4.stl is good
   erc5a.stl has 50 degenerate facets
   all of these faults were susceptible to autocorrection by my copy of Slic3r, other software is available that can also clean up the mesh. Enjoy...