Stack Overflow banishes belligerent blather with bespoke bot - but will it work?

'The mean police, they live inside of my head, the mean police, they come to me in my bed...'

Online Q&A site Stack Overflow aspires to be "a welcoming and friendly place," and to make that so, the biz has deployed sentiment-sniffing code to catch unkind commentary lest it drive members of its online community away."