Izvestia - a look inside

I can't quite remember, how on Earth I got into this building, but never mind. That's Izvestia newspaper publishers. Look at the walls - the purest Soviet design with workers and peasants reading newspapers. Ironically, they are reading Pravda (the rivalry between these two Bolshevik papers at some point got so acute, that the Party had to interfere).
They also show off some old curiosities - like a typewriter that belonged to Bukharin, Izvestia's editor-in-chief, shot by Stalin.
 

 
Bukharin got shot after a show trial in 1938. On the typewriter the letter "B" is blackened. Is it because they wanted to erase memory of its former owner - B (ukharin)? Or just because the owner printed his name too often?