write_inheritable_hash

# File activesupport/lib/active_support/core_ext/class/inheritable_attributes.rb, line 111
  def write_inheritable_hash(key, hash)
    write_inheritable_attribute(key, {}) if read_inheritable_attribute(key).nil?
    write_inheritable_attribute(key, read_inheritable_attribute(key).merge(hash))
  end