StopUnlessBifurcating: Check that all nodes in a tree are bifurcating.
Description
Check that all nodes in a tree are bifurcating.
Usage
StopUnlessBifurcating(parent)
Arguments
parent
Integer vector corresponding to the first column of the edge
matrix of a tree of class phylo, i.e. tree$edge[, 1].
Value
Returns NULL, but will stop with an error message if a tree
does not appear to be bifurcating.