filter_network: Filter the network's vertices
In emba: Ensemble Boolean Model Biomarker Analysis

Produce an induced subgraph of the given net igraph object. How many vertices/nodes will be kept in the result graph object is determined by the initial nodes given and the level provided. A level equal to 0 corresponds to a subgraph with only the given nodes, a level equal to 1 to a subgraph with the nodes + their neighbors (the closed neighbourhood set where every node is within 1 edge distnace from the given ones) and a level equal to 2 to a subgraph with the nodes + their neighbors + the nodes neighbor neighbors! (so the neighbourhood of the neighbourhood or every node is within 2 edges distance from the given ones).

1	filter_network(net, nodes, level)

`net`	an igraph object.
`nodes`	character vector of node names. It must be a subset of the nodes of the net object.
`level`	integer. Can be only 0, 1 or 2 and specifies the neighbourhood depth of the result graph.