from collections import defaultdict

data = [
    {'name': 'Alice', 'city': 'New York'},
    {'name': 'Bob', 'city': 'London'},
    {'name': 'Charlie', 'city': 'New York'},
    {'name': 'David', 'city': 'London'},
    {'name': 'Eve', 'city': 'Paris'}
]

# Group people by city
grouped_by_city = defaultdict(list)
for item in data:
    grouped_by_city[item['city']].append(item['name'])

# Convert to a regular dict for output if needed
result = dict(grouped_by_city)
print(result)
# Expected: {'New York': ['Alice', 'Charlie'], 'London': ['Bob', 'David'], 'Paris': ['Eve']}

# Example with a different default_factory
word_counts = defaultdict(int)
sentence = "hello world hello python"
for word in sentence.split():
    word_counts[word] += 1
print(dict(word_counts))
# Expected: {'hello': 2, 'world': 1, 'python': 1}