check_ns

# File lib/rss/parser.rb, line 426
    def check_ns(tag_name, prefix, ns, require_uri, ignore_unknown_element=nil)
      if _ns(ns, prefix) == require_uri
        true
      else
        if ignore_unknown_element.nil?
          ignore_unknown_element = @ignore_unknown_element
        end

        if ignore_unknown_element
          false
        elsif @do_validate
          raise NSError.new(tag_name, prefix, require_uri)
        else
          # Force bind required URI with prefix
          @ns_stack.last[prefix] = require_uri
          true
        end
      end
    end