d = {"key1": 10, "key2": 23}
if "key1" in d: print("this will execute")
if "nonexistent key" in d: print("this will not")

my_dict = {'key1': 'value1', 'key2': 'value2'}
# Method 1: using the 'in' operator
if 'key1' in my_dict: print("'key1' exists in the dictionary")
# Method 2: using the built-in get() method
if my_dict.get('key2'): print("'key2' exists in the dictionary")
# Method 3: using try-except block
try: value = my_dict['key3'] print("'key3' exists in the dictionary")
except KeyError: print("'key3' does not exist in the dictionary")

dict = {"key1": 1, "key2": 2}
if "key1" in dict:	print dict["key1]
>> 1

# Example dictionary
my_dict = {"key1": "value1", "key2": "value2", "key3": "value3"}
# Method 1: Using `in` operator
if "key2" in my_dict: print("Key 'key2' exists in dictionary.")
# Method 2: Using `get()` method
if my_dict.get("key2"): print("Key 'key2' exists in dictionary.")

# in tests for the existence of a key in a dict:
d = {"key1": 10, "key2": 23}
if "key1" in d: print("this will execute")
if "nonexistent key" in d: print("this will not")
# Use dict.get() to provide a default value when the key does not exist:
d = {}
for i in range(10): d[i] = d.get(i, 0) + 1
# To provide a default value for every key, either use dict.setdefault() on each assignment:
d = {}
for i in range(10): d[i] = d.setdefault(i, 0) + 1
# or use defaultdict from the collections module:
from collections import defaultdict
d = defaultdict(int)
for i in range(10): d[i] += 1

my_dict = {'name': 'John', 'age': 25, 'country': 'USA'}
# Method 1: Using the 'in' operator
if 'age' in my_dict: print("Key 'age' exists in the dictionary.")
else: print("Key 'age' does not exist in the dictionary.")
# Method 2: Using the 'get' method
if my_dict.get('country') is not None: print("Key 'country' exists in the dictionary.")
else: print("Key 'country' does not exist in the dictionary.")