class_docstr: Abstract class for one-to-one logical operators, which
  have one input and one output dependency.
code: def input_dependency(self) -> LogicalOperator:
      return self._input_dependencies[0]
  
file_path: ray/python/ray/data/_internal/logical/operators/one_to_one_operator.py
imports: import abc
  from typing import Optional
  from ray.data._internal.logical.interfaces import LogicalOperator
label_desc: Use image node_id 2 for calling the AbstractOneToOne obj's underlying member method code with example usage: obj.input_dependency() and returns: self