class Dry::Core::ClassBuilder

def create_base(namespace, name, parent)
  if namespace.const_defined?(name, false)
    existing = namespace.const_get(name)
    unless existing <= parent
      raise ParentClassMismatch, "#{ existing.name } must be a subclass of #{ parent.name }"
    end
    existing
  else
    klass = Class.new(parent || Object)
    namespace.const_set(name, klass)
    klass
  end
end