Given a digraph $G'$ and a node $v \in V(G')$, define the contraction of node $v$ as follows. Let $u_1, u_2, \ldots, u_p$ be the in-neighbours of $v$ and $w_1, w_2, \ldots, w_q$ be the out-neighbours of $v$. The contraction of $v$ is obtained by adding the edge $u_i w_j$ for each $i \in [p]$, $j \in [q]$.
Is there a standard place where node contraction is defined as above?
