Wilson Score Confidence interval

Not sure where I got this snipplet - most likely from reddit code or discussion.

from math import sqrt

def confidence_fixed(ups, downs):
    if ups == 0:
        return -downs
    n = ups + downs
    z = 1.64485 #1.0 = 85%, 1.6 = 95%
    phat = float(ups) / n
    return (phat+z*z/(2*n)-z*sqrt((phat*(1-phat)+z*z/(4*n))/n))/(1+z*z/n)

Like for like in Julia

function confidence_fixed(ups,downs)
      if ups==0
         return -downs
      end
      n = ups + downs
      z = 1.64485 #1.0 = 85%, 1.6 = 95%
      phat = float(ups)/n
          return (phat+z*z/(2*n)-z*sqrt((phat*(1-phat)+z*z/(4*n))/n))/(1+z*z/n)
 end