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: has_many.rb
    path of file: ./repos/spyke/lib/spyke/associations
    
    the code of the file until where you have to start completion: module Spyke
  module Associations
    class HasMany < Association
      def initialize(*args)
        super
        @options.reverse_merge!(uri: "#{parent_path}/:
    
        def combine_with_existing(incoming)
          return incoming unless primary_keys_present_in_existing?
          combined = embedded_attributes + incoming
          group_by_primary_key(combined).flat_map do |primary_key, hashes|
            if primary_key.present?
              hashes.reduce(:merge)
            else
              hashes
            end
          end