build

# File activerecord/lib/active_record/associations/association_collection.rb, line 115
      def build(attributes = {}, &block)
        if attributes.is_a?(Array)
          attributes.collect { |attr| build(attr, &block) }
        else
          build_record(attributes) do |record|
            block.call(record) if block_given?
            set_belongs_to_association_for(record)
          end
        end
      end