<｜begin▁of▁sentence｜>### Instruction:
Given an instantiated UniqueIdGenerator and two items ('item1' and 'item2') which have been assigned unique IDs, can you use the '__contains__' method to check if 'item1' already has an ID? Print the result.
### Response:
from networkx.utils import UniqueIdGenerator

# Instantiate a UniqueIdGenerator
uids = UniqueIdGenerator()

# Add some IDs
uid1 = uids['item1']
uid2 = uids['item2']

# Check if 'item1' has an ID
item_exists = 'item1' in uids

# Print the result
print(item_exists)
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