# File lib/rr/injections/double_injection.rb, line 56
        def verify(*subjects)
          subject_classes = subjects.empty? ?
            Injections::DoubleInjection.instances.keys :
            subjects.map {|subject| class << subject; self; end}
          subject_classes.each do |subject_class|
            instances.include?(subject_class) &&
              instances[subject_class].keys.each do |method_name|
                verify_double(subject_class, method_name)
              end &&
              instances.delete(subject_class)
          end
        end