code: def list_available() -> list:
      from matchzoo.engine.base_metric import BaseMetric
      from matchzoo.utils import list_recursive_concrete_subclasses
  
      return list_recursive_concrete_subclasses(BaseMetric)
  
imports: from .precision import Precision
  from .average_precision import AveragePrecision
  from .discounted_cumulative_gain import DiscountedCumulativeGain
  from .mean_reciprocal_rank import MeanReciprocalRank
  from .mean_average_precision import MeanAveragePrecision
  from .normalized_discounted_cumulative_gain import NormalizedDiscountedCumulativeGain
label_desc: Use image node_id 1 for calling a global function with example usage: list_available() and returns: list_recursive_concrete_subclasses