diff --git a/src/Edit.jl b/src/Edit.jl
index 77c7dc6..265f769 100644
--- a/src/Edit.jl
+++ b/src/Edit.jl
@@ -62,6 +62,11 @@ function BioGenerics.rightposition(e::Edit)
     end
 end
 
+"""
+    _lendiff(edit::Edit)
+
+Gets the number of bases that `edit` adds to the reference sequence
+"""
 function _lendiff(edit::Edit)
     x = _mutation(edit)
     # Each edit type has logic for its length, we just need to know what direction to go