code: def unify(self, other):
      assert isinstance(other, NatBase)
      if NatVariable._nat is not None:
          return NatVariable._nat.unify(other)
      else:
          NatVariable._nat = other
          return True
  
file_path: hail/hail/python/hail/expr/nat.py
imports: import abc
label_desc: Use image node_id 2 for calling the NatVariable obj's underlying member method code with example usage: obj.unify(other) and returns: NatVariable, True