class ActiveSupport::HashWithIndifferentAccess

This value can be later fetched using either +:key+ or 'key'.

hash[:key] = 'value'
hash = ActiveSupport::HashWithIndifferentAccess.new

Assigns a new value to the hash:

def []=(key, value)
  regular_writer(convert_key(key), convert_value(value, for: :assignment))
end