class_docstr: Logical operator for union.
class_docstr_tok: ["Logical","operator","for","union","."]
code: def estimated_num_outputs(self):
      total_num_outputs = 0
      for input in self._input_dependencies:
          num_outputs = input.estimated_num_outputs()
          if num_outputs is None:
              return None
          total_num_outputs += num_outputs
      return total_num_outputs
  
file_path: ray/python/ray/data/_internal/logical/operators/n_ary_operator.py
imports: from typing import Optional
  from ray.data._internal.logical.interfaces import LogicalOperator
label_desc: Use image node_id 2 for calling the Union obj's underlying member method code with example usage: obj.estimated_num_outputs() and returns: total_num_outputs, None