def _write_field(self, value):
class_name = str(value.__class__)<EOL>if class_name not in self.handlers:<EOL><INDENT>raise ValueError('<STR_LIT>'.format(class_name))<EOL><DEDENT>handler = self.handlers[class_name]<EOL>handler(value, self._file)<EOL>
Write a single field to the destination file.

:param T value: The value of the field.