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<?php $arr = array ( 0 => 'nested array', 1 => 'nested array', 2 => 'nested array', 3 => 'nested array', 4 => 'nested array', 5 => 'nested array', ); $arr[null] = 'jam'; var_dump(key(array_diff(array_keys(array_values($arr)), array_keys($arr))))?:NULL;
Output for git.master, git.master_jit, rfc.property-hooks
int(6)

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