def as (user, quiet: false)
      let :@user => user do
        log.info "as #{user}", quiet: quiet do
          yield
        end
      end
    end
def as (user, quiet: false)
      let :@user => user do
        log.info "as #{user}", quiet: quiet do
          yield
        end
      end
    end
Yield with a temporary username override
 @macro quietable