@classmethod<EOL><INDENT>def reassemble(cls, fields, document):<DEDENT>
for field_name in cls._instructions:<EOL><INDENT>if field_name in fields:<EOL><INDENT>maker = cls._instructions[field_name]<EOL>with maker.target(document):<EOL><INDENT>document[field_name] = maker()<EOL><DEDENT><DEDENT><DEDENT>
Take a previously assembled document and reassemble the given set of
fields for it in place.