update api documentation

pkg/obitax/lca.go

@@ -1,16 +1,35 @@
 package obitax
 
 import (
-	log "github.com/sirupsen/logrus"
+	"fmt"
 )
 
+// LCA computes the Lowest Common Ancestor (LCA) of two Taxon instances.
+// It traverses the paths from both taxa to the root and finds the deepest
+// common node in the taxonomy hierarchy.
+//
+// Parameters:
+//   - t2: A pointer to another Taxon instance to find the LCA with.
+//
+// Returns:
+//   - A pointer to the Taxon representing the LCA of the two taxa, or an error
+//     if either of the taxa is nil, if they are not in the same taxonomy, or
+//     if the taxonomy is unrooted.
 func (t1 *Taxon) LCA(t2 *Taxon) (*Taxon, error) {
-	if t1 == nil {
-		log.Panicf("Try to get LCA of nil taxon")
+	if t1 == nil || t1.Node == nil {
+		return nil, fmt.Errorf("try to get LCA of nil taxon")
 	}
 
-	if t2 == nil {
-		log.Panicf("Try to get LCA of nil taxon")
+	if t2 == nil || t2.Node == nil {
+		return nil, fmt.Errorf("try to get LCA of nil taxon")
+	}
+
+	if t1.Taxonomy != t2.Taxonomy {
+		return nil, fmt.Errorf("taxa are not in the same taxonomy")
+	}
+
+	if !t1.Taxonomy.HasRoot() {
+		return nil, fmt.Errorf("taxa belong to an unrooted taxonomy")
 	}
 
 	p1 := t1.Path()