class_docstr: A backpressure policy that caps the concurrency of each operator.
  
  The concurrency cap limits the number of concurrently running tasks.
  It will be set to an intial value, and will ramp up exponentially.
  
  The concrete stategy is as follows:
  - Each PhysicalOperator is assigned an initial concurrency cap.
  - An PhysicalOperator can run new tasks if the number of running tasks is less
    than the cap.
  - When the number of finished tasks reaches a threshold, the concurrency cap will
    increase.
code: def can_add_input(self, op: "PhysicalOperator") -> bool:
      metrics = op.metrics
      while self._cap_multiplier > 1 and metrics.num_tasks_finished >= (
          self._concurrency_caps[op] * self._cap_multiply_threshold
      ):
          self._concurrency_caps[op] *= self._cap_multiplier
          logger.debug(
              f"Concurrency cap for {op} increased to {self._concurrency_caps[op]}"
          )
      return metrics.num_tasks_running < self._concurrency_caps[op]
  
file_path: ray/python/ray/data/_internal/execution/backpressure_policy/concurrency_cap_backpressure_policy.py
imports: import logging
  from typing import TYPE_CHECKING
  import ray
  from .backpressure_policy import BackpressurePolicy
label_desc: Use image node_id 2 for calling the ConcurrencyCapBackpressurePolicy obj's underlying member method code with example usage: obj.can_add_input(op) and returns: unknown