The incoming two-path effect describes the propensity of dyads to interact
based on the number of past incoming two-paths between them. By default, the
statistic at timepoint t for the dyad (i,j) is computed as the sum of the
minimum occurrences of past (j,h) and (h,i) events across all actors h.
When the unique parameter is set to TRUE, a different approach is taken.
In this case, the statistic counts the number of actors h that contribute to
the creation of a new, distinct two-path between actors i and j.
Additionally, it is possible to specify a scaling method using the scaling
parameter.
Please note that the incoming two-path effect, 'itp', is exclusively defined
for directed events.