* topo
A tiny unix-like utility for resolving arbitrary graph dependencies.
It takes no arguments and has no flags.
It also provides a tiny shell script that visualizes graphs.

* Interaction
| STDIN  | input graph |
| STDOUT | result      |
| STDERR | errors      |

** Input
*** Form 1
These are lines that look like two names separated by a space.
Let's say these two names were =a= and =b=.
This means =a= is being blocked (or depending on) =b=.
=b= would first have to be resolved for =a= to be able to run.

*** Form 2
These are lines that look like a single name with no space.
Let's say the line was =a=.
This means =a= is complete, allowing other nodes which depend on it to be run if they have no other dependencies unresolved.

*** Form 3
These are empty lines.
After receiving this query it outputs on the STDOUT nodes which can be resolved.
Output is a single line containing names of nodes followed by a space.