@typecheck_method(old=IR, fields=sequenceof(str))
def __init__(self, old, fields):
    super().__init__(old)
    self.old = old
    self.fields = fields
@typecheck_method(old=IR, fields=sequenceof(str))
def __init__(self, old, fields):
    super().__init__(old)
    self.old = old
    self.fields = fields