Lab 19.1: Error in global yaml definition

Hello,
In the federation Prometheus definition, second target is wrong. It says 'prob-b' when it should say 'prom-b'. The right definition is:

global:
  scrape_interval: 5s
  evaluation_interval: 5s

scrape_configs:
  - job_name: 'federate'
    honor_labels: true
    metrics_path: '/federate'
    params:
      'match[]':
        - '{__name__=~"job:.*"}'
    static_configs:
      - targets:
        - 'prom-a:9090'
        - 'prom-b:9090'