diff --git a/loop/repetitions.py b/loop/repetitions.py
index fd020a3..c3e52ce 100644
--- a/loop/repetitions.py
+++ b/loop/repetitions.py
@@ -4,21 +4,35 @@ import re
 
 def migrate(db, habitlist, events):
     c = db.cursor()
-    habitlist = simple_habits_list(c, habitlist)
+    habits = simple_habits_list(c, habitlist)
+    repetitions = extract_all_repetitions(habits, events)
+    for rep in repetitions:
+        add_to_database(c, rep["id"], rep["timestamp"])
+
+
+def extract_all_repetitions(habits, events):
+    """Return list of all repetitions found of habits in events passed in.
+    Parameters:
+    habits (list): Collection of habits, with minimum necessary fields description and id.
+    events (list): Collection of events, with minimum necessary field end.
+    Returns:
+    repetitions (list): Collection of events transformed into Loop repetitions.
+                        Contains fields id, timestamp, value (for ranges).
+    """
+    repetitions = []
     for event in events:
         text = event["note"]
         tags = extract_tags(text)
-        for habit in habitlist:
+        for habit in habits:
             for tag in tags:
                 if habit["description"] in tag[0]:
-                    print(
-                        f"register event: {habit['name']} in {text} at {event['end']}"
-                    )
-                    add_to_database(c, habit["id"], event["end"])
+                    print(f"found event: {habit['name']} in {text} at {event['end']}")
+                    repetitions.append({"id": habit["id"], "timestamp": event["end"]})
+    return repetitions
 
 
 def extract_tags(text, tagmarker="#"):
-    """Returns lists of tuples of all event tags found in text.
+    """Return lists of tuples of all event tags found in text.
     Parameters:
     text (str): The text to search through.
     tagmarker (str): Optional character marking beginning of tag, defaults to '#'.
@@ -30,6 +44,14 @@ def extract_tags(text, tagmarker="#"):
 
 
 def simple_habits_list(c, habitlist):
+    """Return simplified collection of habits, only carrying name, tag, id.
+    Parameters:
+    c (sqlite.db.cursor): SQL cursor of database to query.
+    habitlist (list): Full habit collection to return a simplified view of.
+    Returns:
+    habitlist (list): Simple habitlist, habit name, tag, and id.
+                      Copy of original, changes do not affect original.
+    """
     simple = []
     for h in habitlist:
         simple.append(
@@ -43,6 +65,13 @@ def simple_habits_list(c, habitlist):
 
 
 def fetch_habit_id(c, uuid):
+    """Return sqlite internal id for habit with uuid.
+    Parameters:
+    c (sqlite.db.cursor): SQL cursor of database to query.
+    uuid (str): Unique id of habit to query for.
+    Returns:
+    id (int): SQLite internal id for habit queried for.
+    """
     c.execute("select id from Habits where uuid = ?", ([uuid]))
     id = c.fetchone()
     if id is not None:
@@ -67,5 +96,5 @@ def add_to_database(cursor, habit_id, timestamp, value=2):
         )
     except sqlite3.IntegrityError:
         # TODO better error handling
-        print("fail to register: not unique")
+        print(f"fail to register {habit_id}: timestamp {timestamp} not unique")
         pass