MadelineProto/docs/API_docs/methods/account_checkUsername.md

Method: account_checkUsername

Parameters:

Name	Type	Required
username	string	Required

Return type: Bool

Example:

$MadelineProto = new \danog\MadelineProto\API();
if (isset($token)) {
    $this->bot_login($token);
}
if (isset($number)) {
    $sentCode = $MadelineProto->phone_login($number);
    echo 'Enter the code you received: ';
    $code = '';
    for ($x = 0; $x < $sentCode['type']['length']; $x++) {
        $code .= fgetc(STDIN);
    }
    $MadelineProto->complete_phone_login($code);
}

$Bool = $MadelineProto->account_checkUsername(['username' => string, ]);