`slow-odgi`: `extract`

[anshumanmohan]

Just making a note that odgi extract is wicked cool and I'd like to implement it in slow-odgi sometime.

https://hackmd.io/@AndreaGuarracino/SyhbiKuE2#Lipoprotein-A-graph

odgi extract -i LPA.og -n 23 -c 1 -d 0 -o LPA.21_23_G_GT.og

The instruction extracts:

• the node with ID 23 (-n 23),
• the nodes reachable from this node following a single edge (-c 1) in the graph topology,
• the edges connecting all the extracted nodes, and
• the paths traversing all the extracted nodes.