old_contents: from app import db
  from app.mod_auth.model import User
  
  class Category(db.Document):
      # The name of the category.
      name = db.StringField(required = True)
  
  class Entry(db.Document):
      # The amount of the entry.
      amount = db.DecimalField(precision = 2, required = True)
  
      # A short description for the entry.
      description = db.StringField(required = True)
  
      # The owner of the entry.
      # Should the owner be deleted, we also want to delete all of his entries.
      owner = db.ReferenceField(User, reverse_delete_rule = db.CASCADE, required = True)
  
      # The category of this entry.
      category = db.ReferenceField(Category, required = True)
  
  def sumEntries():
      return sum([entry.amount for entry in Entry.objects if entry.amount > 0])
  
new_contents: from app import db
  from app.mod_auth.model import User
  
  class Category(db.Document):
      # The name of the category.
      name = db.StringField(required = True)
  
  class Entry(db.Document):
      # The amount of the entry.
      amount = db.DecimalField(precision = 2, required = True)
  
      # A short description for the entry.
      description = db.StringField(required = True)
  
      # The owner of the entry.
      # Should the owner be deleted, we also want to delete all of his entries.
      owner = db.ReferenceField(User, reverse_delete_rule = db.CASCADE, required = True)
  
      # The category of this entry.
      category = db.ReferenceField(Category, required = True)
  
subject: Remove unused sumEntries function