nl_tokens: Calculate the value of keyProvider
pl_tokens: async function __calcKeyProvider ( keyProvider ) { if ( ! keyProvider ) { return [ ] ; } // if keyProvider is function if ( keyProvider . apply && keyProvider . call ) { keyProvider = keyProvider ( ) ; } // resolve for Promise keyProvider = await Promise . resolve ( keyProvider ) ; if ( ! Array . isArray ( keyProvider ) ) { keyProvider = [ keyProvider ] ; } for ( let key of keyProvider ) { if ( ! EvtKey . isValidPrivateKey ( key ) ) { throw <mask> Error ( "Invalid private key" ) ; } } return keyProvider ; }