class_docstr: Base semiring class.
  
  Based on description in:
  
  * Semiring parsing :cite:`goodman1999semiring`
code: def plus(cls, a, b):
      return cls.sum(torch.stack([a, b], dim=-1))
  
imports: import torch
label_desc: Use image node_id 9 for calling the Semiring obj's underlying member method code with example usage: obj.plus(cls, a, b) and returns: cls