code: def _with_missing(self, key, Ty=Any):
      if key in self.output_schema:
          return self, self.output_schema[key]
  
      Ty_ = self.input_schema.get(key, Ty)
      combined = Union[Ty, Ty_]
      clone = self.copy()
  
      clone.input_schema.fields[key] = combined
      return clone, combined
  
imports: from dataclasses import dataclass, field
  from functools import singledispatch
  from typing import Any, Dict, Type, Union
  import numpy
label_desc: Use image node_id 1 for calling the SchemaTracker obj's underlying member method code with example usage: obj._with_missing(key, Ty) and returns: clone,  combined, self,  self