public Leaf FindLeaf(string s, bool precisely)
{
BranchNode branch = FindBranch(s);
if (branch == null)
{
return(null);
}
if (precisely)
{
return(branch.leaf);
}
var leaves = branch.FindAllLeaves();
if (leaves.Length == 1)
{
return(leaves[0]);
}
return(null);
}
