code: func dispatchHealthcheck(d dispatchRequest, c *instructions.HealthCheckCommand) error {
  	runConfig := d.state.runConfig
  	if runConfig.Healthcheck != nil {
  		oldCmd := runConfig.Healthcheck.Test
  		if len(oldCmd) > 0 && oldCmd[0] != "NONE" {
  			fmt.Fprintf(d.builder.Stdout, "Note: overriding previous HEALTHCHECK: %v\n", oldCmd)
  		}
  	}
  	runConfig.Healthcheck = c.Health
  	return d.builder.commit(d.state, fmt.Sprintf("HEALTHCHECK %q", runConfig.Healthcheck))
  }
docs: // HEALTHCHECK foo
  //
  // Set the default healthcheck command to run in the container (which may be empty).
  // Argument handling is the same as RUN.
  //