Deserialize objects and data from XML.
This method will begin to parse the object t. The type t must be serializable. Parsing can be completed by calling advance() repeatedly, or by calling finish().
Returns true if the object passed to begin() could be parsed completely, otherwise false is returned. If false is returned, no further progress can be made, until more data becomes available. When parsing is complete, references can be fixed up by calling fixup().
This method will finish parsing of the object started by begin(). After all objects have been parsed, references can be fixed up by calling fixup()
Weak references between the parsed objects can be fixed up calling this method. Fixup has to happen after all objects have been parsed so references can be forward and backward in the object stream.