set.union() / set.intersection() / set.difference()

# Union (elements in either set)
set1.union(set2)
set1 | set2

# Intersection (elements in both sets)
set1.intersection(set2)
set1 & set2

# Difference (elements in set1 but not in set2)
set1.difference(set2)
set1 - set2

# Symmetric difference (elements in one set but not both)
set1.symmetric_difference(set2)
set1 ^ set2

# Prepare two sets.
python_users = {'Alice', 'Bob', 'Charlie', 'Diana'}
java_users   = {'Bob', 'Eve', 'Diana', 'Frank'}

# Union: users who use either language
print(python_users | java_users)
# Outputs: {'Alice', 'Bob', 'Charlie', 'Diana', 'Eve', 'Frank'}

# Intersection: users who use both languages
print(python_users & java_users)
# Outputs: {'Bob', 'Diana'}

# Difference: users who use only Python
print(python_users - java_users)
# Outputs: {'Alice', 'Charlie'}

# Symmetric difference: users who use only one language
print(python_users ^ java_users)
# Outputs: {'Alice', 'Charlie', 'Eve', 'Frank'}

# You can also use methods for the same operations.
union_set = python_users.union(java_users)
inter_set = python_users.intersection(java_users)
diff_set  = python_users.difference(java_users)

# In-place operators update the set itself.
python_users &= java_users
print(python_users)  # Updated to the intersection result.

# You can chain operations across multiple sets.
a = {1, 2, 3}
b = {2, 3, 4}
c = {3, 4, 5}
print(a & b & c)  # Outputs: {3}
print(a | b | c)  # Outputs: {1, 2, 3, 4, 5}

Set operations can be performed with either methods or operators. When using operators (|, &, -, ^), both operands must be sets. When using methods, any iterable such as a list or tuple can be passed as the argument.

All set operations return a new set without modifying the originals. To update a set in place, use the in-place operators |=, &=, -=, and ^=, or their corresponding methods (update(), intersection_update(), etc.).

The difference operation is order-dependent. A - B and B - A produce different results. If you want elements that belong to neither set, use the symmetric difference (^) instead.

To check subset or superset relationships between sets, see 'set.issubset() / set.issuperset() / set.isdisjoint()'.