module ActiveSupport::Callbacks::ClassMethods

def skip_callback(name, *filter_list, &block)

already been set (unless the :raise option is set to false).
An ArgumentError will be raised if the callback has not

end
skip_callback :validate, :before, :check_membership, if: -> { self.age > 18 }
class Writer < Person

callback is skipped.
:unless options may be passed in order to control when the
Skip a previously set callback. Like +set_callback+, :if or 
def skip_callback(name, *filter_list, &block)
  type, filters, options = normalize_callback_params(filter_list, block)
  options[:raise] = true unless options.key?(:raise)
  __update_callbacks(name) do |target, chain|
    filters.each do |filter|
      callback = chain.find {|c| c.matches?(type, filter) }
      if !callback && options[:raise]
        raise ArgumentError, "#{type.to_s.capitalize} #{name} callback #{filter.inspect} has not been defined"
      end
      if callback && (options.key?(:if) || options.key?(:unless))
        new_callback = callback.merge_conditional_options(chain, if_option: options[:if], unless_option: options[:unless])
        chain.insert(chain.index(callback), new_callback)
      end
      chain.delete(callback)
    end
    target.set_callbacks name, chain
  end
end