* May be the blob itself, or the blob compressed, or just the address
* of the actual blob, depending on $flags.
* @param string|string[] $flags Blob flags, such as 'external' or 'gzip'.
* May be the blob itself, or the blob compressed, or just the address
* of the actual blob, depending on $flags.
* @param string|string[] $flags Blob flags, such as 'external' or 'gzip'.