```ruby
# XXX: Hack!
# XXX: Monkey patch Loofah's whitelist tags
# XXX: This allows configurable tag whitelist
# XXX: where user can specify which tags to keep.
#
# see https://github.com/flavorjones/loofah/blob/master/lib/loofah/html5/whitelist.rb
# for current default whitelist.
if ENV["WLTAGS"]
  tag_list = Loofah::HTML5::WhiteList::ALLOWED_ELEMENTS_WITH_LIBXML2
  tag_list += ENV["WLTAGS"].split
  Loofah::HTML5::WhiteList::send :remove_const, :ALLOWED_ELEMENTS_WITH_LIBXML2
  Loofah::HTML5::WhiteList::const_set :ALLOWED_ELEMENTS_WITH_LIBXML2, tag_list
end
```

Use dot for method call
user
```ruby
# XXX: Hack!
# XXX: Monkey patch Loofah's whitelist tags
# XXX: This allows configurable tag whitelist
# XXX: where user can specify which tags to keep.
#
# see https://github.com/flavorjones/loofah/blob/master/lib/loofah/html5/whitelist.rb
# for current default whitelist.
if ENV["WLTAGS"]
  tag_list = Loofah::HTML5::WhiteList::ALLOWED_ELEMENTS_WITH_LIBXML2
  tag_list += ENV["WLTAGS"].split
  Loofah::HTML5::WhiteList.send :remove_const, :ALLOWED_ELEMENTS_WITH_LIBXML2
  Loofah::HTML5::WhiteList.const_set :ALLOWED_ELEMENTS_WITH_LIBXML2, tag_list
end
```
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