code: def csv(ctx, dst):
      
      sm = Smother.load(ctx.obj['report'])
      semantic = ctx.obj['semantic']
      writer = _csv.writer(dst, lineterminator='\n')
      dst.write("source_context, test_context\n")
      writer.writerows(sm.iter_records(semantic=semantic))
docs: Flatten a coverage file into a CSV
      of source_context, testname