…Context.

It creates a set of `.sources` using all the supplied `Attribute`s relying the behavior of `Attribute` to not render null strings and/or `.empty` nodes.

I tried to use the `.if` syntax, but got a compiler error. I am leaving the commented code in case there is a better way to implement this.

Changed Plot.Image to Image (this was developed in a separate repo and then pulled into this fork, it was needed there, but is not needed here).
Replaced two ternary ops with `.unwrap` in the `Picture` `body`.

Changed one final `Plot.Image` to `Image`
Cleaned up some formatting and black lines. :-)