How to get the hydra:member

Question

this is normal output and i want to get hydra:member->[0]

stdClass Object ( [@context] => /contexts/Message [@id] => /messages [@type] => hydra:Collection [hydra:member] => Array ( [0] => stdClass Object

how to decode the [hydra:member]

my code

$js = json_decode($result);
$res = $js->hydra:member;
print_r($res);

output

Parse error: syntax error, unexpected ':'