Lambda Functions lambda x: x * 2 def double(x): return x * 2 in x * 2 ⚡ instant out λ lambda def double(x): result = x * 2 return result named · multi-line · reusable 5 10 vs sorted(lst, key=lambda x: x[1]) input list ('Bob', 30) ('Al', 25) ('Zoe', 28) λ x: x[1] key func keys 30 25 28 sort sorted ('Al', 25) ('Zoe', 28) ('Bob', 30) lambda is anonymous · single-expression · inline