def remove_migration_methods
      # remove the migrate_<attribute> methods
      @mgt_mths.each do | klass, hash|
        hash.each_value do |sym|
          while klass.method_defined?(sym)
            klass.instance_method(sym).owner.module_eval { remove_method(sym) }
          end
        end
      end
      # remove the migrate method
      @creatable_classes.each do |klass|
        while (k = klass.instance_method(:migrate).owner) < Migratable
          k.module_eval { remove_method(:migrate) }
        end
      end
      # remove the target extract method
      remove_extract_method(@target) if @extract
    end
def remove_migration_methods
      # remove the migrate_<attribute> methods
      @mgt_mths.each do | klass, hash|
        hash.each_value do |sym|
          while klass.method_defined?(sym)
            klass.instance_method(sym).owner.module_eval { remove_method(sym) }
          end
        end
      end
      # remove the migrate method
      @creatable_classes.each do |klass|
        while (k = klass.instance_method(:migrate).owner) < Migratable
          k.module_eval { remove_method(:migrate) }
        end
      end
      # remove the target extract method
      remove_extract_method(@target) if @extract
    end
Cleans up after the migration by removing the methods injected by migration
 shims.