class Airbrake::TDigest

def percentile(p)
  is_array = p.is_a? Array
  p = [p] unless is_array
  p.map! do |item|
    unless (0..1).cover?(item)
      raise ArgumentError, "p should be in [0,1], got #{item}"
    end
    if size == 0
      nil
    else
      _cumulate(exact: true)
      h = @size * item
      lower, upper = bound_mean_cumn(h)
      if lower.nil? && upper.nil?
        nil
      elsif upper == lower || lower.nil? || upper.nil?
        (lower || upper).mean
      elsif h == lower.mean_cumn
        lower.mean
      else
        upper.mean
      end
    end
  end
  is_array ? p : p.first
end