I ran into an incomprehensible moment in Shield's book C # 4.0, what does it mean to have worked?

Question

Machine learning

I ran into an incomprehensible moment. What does it mean to have worked? It's a typo? Or a reduction?
Quote: C++ was developed in 1979 by Bjarne Stroustrup at Bell Laboratories based in Murray Hill, NY.

Answer 1

C++ was developed in 1979 by Bjarne Stroustrup at Bell Laboratories based in Murray Hill, NY.

Apparently " worked "
"r" and "o" are next to each other on the keyboard
Congratulations - you found a typo