You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: unsettable.rb
    path of file: ./repos/mongoid/lib/mongoid/persistable
    
    the code of the file until where you have to start completion: # frozen_string_literal: true
# rubocop:todo all

module Mongoid
  module Persistable

    # Defines behavior for $unset operations.
    module Unsettable
      extend ActiveSupport::Concern

      # Perform an $unset operation on the provided fields and in the
      # values in the document in memory.
  
    
      def unset(*fields)
        prepare_atomic_operation do |ops|
          fields.flatten.each do |field|
            normalized = database_field_name(field)
            if executing_atomically?
              process_attribute normalized, nil
            else
              attributes.delete(normalized)
            end
            ops[atomic_attribute_name(normalized)] = true
          end
          { "$unset" => ops }
        end