old_contents: from motor.motor_asyncio import AsyncIOMotorClient
  
  class Database(object):
      def __init__(self, uri):
          self.client = AsyncIOMotorClient(uri)
          self.db = self.client['fogeybot']
          self.collection = self.db['users']
  
      async def test_connection(self):
          await self.collection.count()
  
      async def get_mmr(self, discord_id):
          doc = await self.collection.find_one({'_id': {'$eq': str(discord_id)}})
          if doc is None:
              return None
  
          return doc.get('mmr')
  
      async def set_mmr(self, discord_id, mmr):
          await self.collection.update({'_id': str(discord_id)}, {'$set': {'mmr': mmr}})
  
      async def lookup_battle_tag(self, discord_id):
          doc = await self.collection.find_one({'_id': {'$eq': str(discord_id)}})
          if doc is None:
              return {}
  
          return doc
  
      async def register_battle_tag(self, discord_id, battle_tag, mmr):
          existing = await self.collection.find_one({'_id': {'$eq': str(discord_id)}})
          doc = {'battle_tag': battle_tag, 'mmr': mmr}
  
          if existing:
              await self.collection.update({'_id': str(discord_id)}, {'$set': doc})
          else:
              await self.collection.insert({'_id': str(discord_id), **doc})
  
      async def unregister_battle_tag(self, discord_id):
          await self.collection.remove({'_id': {'$eq': str(discord_id)}})
  
new_contents: from motor.motor_asyncio import AsyncIOMotorClient
  
  class Database(object):
      def __init__(self, uri):
          self.client = AsyncIOMotorClient(uri)
          self.db = self.client['fogeybot']
          self.collection = self.db['users']
  
      async def test_connection(self):
          await self.collection.count()
  
      async def get_mmr(self, discord_id):
          doc = await self.collection.find_one({'_id': {'$eq': discord_id}})
          if doc is None:
              return None
  
          return doc.get('mmr')
  
      async def set_mmr(self, discord_id, mmr):
          await self.collection.update({'_id': discord_id}, {'$set': {'mmr': mmr}})
  
      async def lookup_battle_tag(self, discord_id):
          doc = await self.collection.find_one({'_id': {'$eq': discord_id}})
          if doc is None:
              return {}
  
          return doc
  
      async def register_battle_tag(self, discord_id, battle_tag, mmr):
          existing = await self.collection.find_one({'_id': {'$eq': discord_id}})
          doc = {'battle_tag': battle_tag, 'mmr': mmr}
  
          if existing:
              await self.collection.update({'_id': discord_id}, {'$set': doc})
          else:
              await self.collection.insert({'_id': discord_id, **doc})
  
      async def unregister_battle_tag(self, discord_id):
          await self.collection.remove({'_id': {'$eq': discord_id}})
  
subject: Revert only-string change