Task: Cheryl's birthday
Go: package main

import (
    "fmt"
    "time"
)

type birthday struct{ month, day int }

func (b birthday) String() string {
    return fmt.Sprintf("%s %d", time.Month(b.month), b.day)
}

func (b birthday) monthUniqueIn(bds []birthday) bool {
    count := 0
    for _, bd := range bds {
        if bd.month == b.month {
            count++
        }
    }
    if count == 1 {
        return true
    }
    return false
}

func (b birthday) dayUniqueIn(bds []birthday) bool {
    count := 0
    for _, bd := range bds {
        if bd.day == b.day {
            count++
        }
    }
    if count == 1 {
        return true
    }
    return false
}

func (b birthday) monthWithUniqueDayIn(bds []birthday) bool {
    for _, bd := range bds {
        if bd.month == b.month && bd.dayUniqueIn(bds) {
            return true
        }
    }
    return false
}

func main() {
    choices := []birthday{
        {5, 15}, {5, 16}, {5, 19}, {6, 17}, {6, 18},
        {7, 14}, {7, 16}, {8, 14}, {8, 15}, {8, 17},
    }

    
    
    var filtered []birthday
    for _, bd := range choices {
        if !bd.monthUniqueIn(choices) {
            filtered = append(filtered, bd)
        }
    }

    
    
    var filtered2 []birthday
    for _, bd := range filtered {
        if !bd.monthWithUniqueDayIn(filtered) {
            filtered2 = append(filtered2, bd)
        }
    }

    
    
    var filtered3 []birthday
    for _, bd := range filtered2 {
        if bd.dayUniqueIn(filtered2) {
            filtered3 = append(filtered3, bd)
        }
    }

    
    
    var filtered4 []birthday
    for _, bd := range filtered3 {
        if bd.monthUniqueIn(filtered3) {
            filtered4 = append(filtered4, bd)
        }
    }

    if len(filtered4) == 1 {
        fmt.Println("Cheryl's birthday is", filtered4[0])
    } else {
        fmt.Println("Something went wrong!")
    }
}

Python: 

from itertools import groupby
from re import split



def main():
    

    month, day = 0, 1
    print(
        
        
        uniquePairing(month)(
            
            
            uniquePairing(day)(
                
                
                monthsWithUniqueDays(False)([
                    
                    tuple(x.split()) for x in
                    split(
                        ', ',
                        'May 15, May 16, May 19, ' +
                        'June 17, June 18, ' +
                        'July 14, July 16, ' +
                        'Aug 14, Aug 15, Aug 17'
                    )
                ])
            )
        )
    )





def monthsWithUniqueDays(blnInclude):
    
    def go(xs):
        month, day = 0, 1
        months = [fst(x) for x in uniquePairing(day)(xs)]
        return [
            md for md in xs
            if blnInclude or not (md[month] in months)
        ]
    return go



def uniquePairing(i):
    
    def go(xs):
        def inner(md):
            dct = md[i]
            uniques = [
                k for k in dct.keys()
                if 1 == len(dct[k])
            ]
            return [tpl for tpl in xs if tpl[i] in uniques]
        return inner
    return ap(bindPairs)(go)





def bindPairs(xs):
    
    return lambda f: f(
        (
            dictFromPairs(xs),
            dictFromPairs(
                [(b, a) for (a, b) in xs]
            )
        )
    )



def dictFromPairs(xs):
    
    return {
        k: [snd(x) for x in m] for k, m in groupby(
            sorted(xs, key=fst), key=fst
        )
    }





def ap(f):
    
    def go(g):
        def fxgx(x):
            return f(x)(
                g(x)
            )
        return fxgx
    return go



def fst(tpl):
    
    return tpl[0]



def snd(tpl):
    
    return tpl[1]


if __name__ == '__main__':
    main()