Determines the number of bytes that would be required to store
value has a fixed-sized type then this function always returned
that fixed size.
In the case that
value is already in serialized form or the size has
already been calculated (ie: this function has been called before)
then this function is O(1). Otherwise, the size is calculated, an
operation which is approximately O(n) in the number of values involved.
Available since: 2.24