# File lib/mongo/collection.rb, line 380
    def insert(doc_or_docs, opts={})
      doc_or_docs = [doc_or_docs] unless doc_or_docs.is_a?(Array)
      doc_or_docs.collect! { |doc| @pk_factory.create_pk(doc) }
      write_concern = get_write_concern(opts, self)
      result = insert_documents(doc_or_docs, @name, true, write_concern, opts)
      result.size > 1 ? result : result.first
    end