Look if the implementation of the binary sorting of nodes works as expected and add tests

[jordanmontt]

Currently the nodes are stores in a collection. We have two types of nodes: the "model nodes" that are the ones that the user send as a parameters; and the graph nodes which are nodes that we use internally as a data structure. We store those nodes in a collection. When we want to search in which graph node is a given user node we need to do a linear search. There is support for doing a binary search.

This issue is to make sure that the binary search is done right and it works on all cases and to add tests.