nodejs version still comes to 4.6.0 though i am using 6.9.4

#!javascript

# You can use any Docker image from Docker Hub or your own container registry
image: node:6.9.4
image: spittet/node-mongodb
pipelines:
  default:
    - step:
        script:  # Modify the commands below to build and test your repository.
          - apt-get update
          - apt-get install -y ruby libssl-dev
          - gem install sass
          - node -v
          - npm --version