def dump(self, filename):
with open(filename, "<STR_LIT:w>") as f:<EOL><INDENT>for name in sorted(self._fields):<EOL><INDENT>self._fields[name].dump(f, name)<EOL><DEDENT><DEDENT>
Dump the registered fields to a file

           Argument:
            | ``filename``  --  the file to write to