A group of friends (n >= 2) have reunited for a get-together after 
a very long time. 
They agree that they will make presentations on holiday destinations 
or expeditions they have been to only if it satisfies **one simple rule**: 
> the holiday/journey being presented must have been visited _only_ by the presenter and no one else from the audience.
Write a program to output the presentation agenda, including the
presenter and their respective presentation titles. 
---
### EXAMPLES
```python
presentation_agenda([
    {'person': 'Abe', 'dest': ['London', 'Dubai']},
    {'person': 'Bond', 'dest': ['Melbourne', 'Dubai']}
]) == [{'person': 'Abe', 'dest': ['London']},
       {'person': 'Bond', 'dest': ['Melbourne']}]
presentation_agenda([
    {'person': 'Abe', 'dest': ['Dubai']},
    {'person': 'Brad', 'dest': ['Dubai']}
]) == []
presentation_agenda([
    {'person': 'Abe', 'dest': ['London', 'Dubai']},
    {'person': 'Bond', 'dest': ['Melbourne', 'Dubai']},
    {'person': 'Carrie', 'dest': ['Melbourne']},
    {'person': 'Damu', 'dest': ['Melbourne', 'Dubai', 'Paris']}
]) == [{'person': 'Abe',  'dest': ['London']},
       {'person': 'Damu', 'dest': ['Paris']}]
```
from collections import Counter

def presentation_agenda(friend_list):
    all_dests = sum((friend['dest'] for friend in friend_list), [])
    uniq_dests = [dest for dest, count in Counter(all_dests).items() if count == 1]
    agenda = []
    for friend in friend_list:
        uniq = [x for x in friend['dest'] if x in uniq_dests]
        if uniq:
            agenda.append({'person': friend['person'], 'dest': uniq})
    return agenda
from collections import Counter

def presentation_agenda(friend_list):
    all_dests = sum((friend['dest'] for friend in friend_list), [])
    uniq_dests = [dest for dest, count in Counter(all_dests).items() if count == 1]
    agenda = []
    for friend in friend_list:
        uniq = [x for x in friend['dest'] if x in uniq_dests]
        if uniq:
            agenda.append({'person': friend['person'], 'dest': uniq})
    return agenda