SNAPSHOTREADABLE functions produces a STRING which contains WarpScript code to regenerate the stack in the exact same state as when
SNAPSHOTREADABLE was called.
Note that some types of objects created by third party functions may not be serializable,
SNAPSHOTREADABLE will emit a STRING of the form
UNSUPPORTED: class xxx when such a type is encountered.
The elements of the stack are consumed.
This is similar to the
SNAPSHOT function but the output is easier to read for a human.