code: func Execute(dsl func(), def Definition) bool {
  	if dsl == nil {
  		return true
  	}
  	initCount := len(Errors)
  	ctxStack = append(ctxStack, def)
  	dsl()
  	ctxStack = ctxStack[:len(ctxStack)-1]
  	return len(Errors) <= initCount
  }
docs: // Execute runs the given DSL to initialize the given definition. It returns true on success.
  // It returns false and appends to Errors on failure.
  // Note that `Run` takes care of calling `Execute` on all definitions that implement Source.
  // This function is intended for use by definitions that run the DSL at declaration time rather than
  // store the DSL for execution by the dsl engine (usually simple independent definitions).
  // The DSL should use ReportError to record DSL execution errors.