docstr: Maps KerasTensors to computed values using `tensor_dict`.
  
  `tensor_dict` maps `KerasTensor` instances to their current values.
docstr_tok: ["Maps","KerasTensors","to","computed","values","using","`","tensor_dict","`",".","`","tensor_dict","`","maps","`","KerasTensor","`","instances","to","their","current","values","."]
code: def fill_in(self, tensor_dict):
      """Maps KerasTensors to computed values using `tensor_dict`.
  
      `tensor_dict` maps `KerasTensor` instances to their current values.
      """
      if self._single_positional_tensor is not None:
          # Performance optimization for most common case.
          # Approx. 70x faster.
          return (tensor_dict[id(self._single_positional_tensor)],), {}
  
      def switch_fn(x):
          if isinstance(x, KerasTensor):
              val = tensor_dict.get(id(x), None)
              if val is not None:
                  return val
          return x
  
      return self.convert(switch_fn)
  
imports: import tree
  from keras.backend import KerasTensor
label_desc: Use image node_id 3 for calling the SymbolicArguments obj's underlying member method code with example usage: obj.fill_in(tensor_dict) and returns: self, tensor_dict,  dict, x, val