Stores the serialised form of this at
data should be large enough. See get_size.
The stored data is in machine native byte order but may not be in fully-normalised form if read from an untrusted source. See get_normal_form for a solution.
As with get_data, to be able to deserialise the serialised variant successfully, its type and (if the destination machine might be different) its endianness must also be available.
This function is approximately O(n) in the size of
the Variant to store
the location to store the serialised data at