code: def filtering_allele_frequency(ac, an, ci) -> Float64Expression:
      """
      Computes a filtering allele frequency (described below)
      for `ac` and `an` with confidence `ci`.
  
      The filtering allele frequency is the highest true population allele frequency
      for which the upper bound of the `ci` (confidence interval) of allele count
      under a Poisson distribution is still less than the variant’s observed
      `ac` (allele count) in the reference sample, given an `an` (allele number).
  
      This function defines a "filtering AF" that represents
      the threshold disease-specific "maximum credible AF" at or below which
      the disease could not plausibly be caused by that variant. A variant with
      a filtering AF >= the maximum credible AF for the disease under consideration
      should be filtered, while a variant with a filtering AF below the maximum
      credible remains a candidate. This filtering AF is not disease-specific:
      it can be applied to any disease of interest by comparing with a
      user-defined disease-specific maximum credible AF.
  
      For more details, see: `Whiffin et al., 2017 <https://www.nature.com/articles/gim201726>`__
  
      Parameters
      ----------
      ac : int or :class:`.Expression` of type :py:data:`.tint32`
      an : int or :class:`.Expression` of type :py:data:`.tint32`
      ci : float or :class:`.Expression` of type :py:data:`.tfloat64`
  
      Returns
      -------
      :class:`.Expression` of type :py:data:`.tfloat64`
      """
      return _func("filtering_allele_frequency", tfloat64, ac, an, ci)
  
imports: from hail.expr.expressions import expr_float64, expr_int32, Float64Expression
  from hail.expr.types import tfloat64
  from hail.typecheck import typecheck
  from hail.expr.functions import _func
label_desc: Use image node_id 1 for calling a global function with example usage: filtering_allele_frequency(ac, an, ci) and returns: _func