prefix_name_for_action

# File actionpack/lib/action_dispatch/routing/mapper.rb, line 1669
          def prefix_name_for_action(as, action) #:nodoc:
            if as
              prefix = as
            elsif !canonical_action?(action, @scope[:scope_level])
              prefix = action
            end
            prefix.to_s.tr('-', '_') if prefix
          end