function microtime(bool $get_as_float = false): *string|float* {}
function gettimeofday(bool $return_float = false): *array|float* {}
function base64_decode(string $str, bool $strict = false): *string|false* {}
function implode(*string|array* $glue, array $pieces): string {}
function substr_replace(
*string|array $str*,
*string|array $replace*,
$start,
$length
) : *string|array|false* {}