What is an example of anaphora?

Dr. Martin Luther King Jr.’s oft-quoted “I Have a Dream” speech employs anaphora extensively. The repetition of the phrase “go back” in the following lines are an example of that:

Go back to Mississippi, go back to Alabama, go back to South Carolina, go back to Georgia, go back to Louisiana, go back to the slums and ghettos of our northern cities, knowing that somehow this situation can and will be changed.”