Error: Multiple include

Configuration
1

I want to include multiple files in a row.
Configure:

  customize:
    !include customize_switch.yaml
    !include customize_sensor_binary.yaml
    !include customize_gen.yaml

I have error:
2017-10-04 20:36:49 ERROR (MainThread) [homeassistant.bootstrap] Error loading /srv/homeassistant/config/configuration.yaml: Config file not found: /srv/homeassistant/config/customize_switch.yaml !include customize_sensor_binary.yaml !include customize_gen.yaml

But in documentaion write:
" !include filename.yaml is the statement that tells Home Assistant to insert the contents of filename.yaml at that point. "