code: def _f_score(
      precision, recall, beta2
  ):  # pylint: disable=invalid-name
      """Returns F-score.
  
      Args:
        precision: a precision score.
        recall: a recall score.
        beta2: a square of the parameter that determines the weight of recall.
  
      A support function to calculate F-score for the single category.
      """
      return _non_nan(
          (beta2 + 1)
          * (precision * recall)
          / ((beta2 * precision) + recall)
      )
  
imports: from trax import fastmath
  from trax import shapes
  from trax.fastmath import numpy
  from trax.layers import base
  from trax.layers import combinators
  from trax.layers import core
label_desc: Use image node_id 5 for calling a global function with example usage: _f_score(precision, recall, beta2) and returns: _non_nan