Usage: keychain.getHardenedDIP15AccountKey(accountIndex = 0, type = 'HDPrivateKey')
Description: Return a safier root path to derivate from

Parameters:

parameters	type	required	Description
accountIndex	number	no (default:0)	set the account index
type	string	no (default:HDPrivateKey)	Enter a valid type (one of: ['HDPrivateKey','HDPublicKey'])

Returns : HDPrivateKey (of path: m/9'/1'/15'/accountIndex' on testnet or m/9'/5'/15'/accountIndex' on livenet)

Example:

const hdPrivateKey = keychain.getHardenedDIP15AccountKey();
const { privateKey } = hdPrivateKey;