_positive_index_of(self, key)
(Really this should be called non_negative_index_of but it felt too long.)
This means that if the key is a negative integer, we have to convert it to the corresponding positive index. This means knowing the length of the HDUList, which in turn means loading all HDUs. Therefore using negative indices on HDULists is inherently inefficient.
Same as index_of, but ensures always returning a positive index or zero.
Hover to see nodes names; edges to Self not shown, Caped at 50 nodes.
Using a canvas is more power efficient and can get hundred of nodes ; but does not allow hyperlinks; , arrows or text (beyond on hover)
SVG is more flexible but power hungry; and does not scale well to 50 + nodes.
All aboves nodes referred to, (or are referred from) current nodes; Edges from Self to other have been omitted (or all nodes would be connected to the central node "self" which is not useful). Nodes are colored by the library they belong to, and scaled with the number of references pointing them