# Clone computing > Do it once. This [[Anti-Pattern|anti-pattern]] happens when you perform an operation similar to a [[Pure Function]] (same input mean same output without side effects) multiple times to avoid creating a temporary [[Variable]]. It's easily solved with a [[Walrus Operator]]. ```python # Don't if int(value) % 2 != 0: do_stuff(int(value)) # Do if (n:=int(value)) % 2 != 0: do_stuff(n) # Or (beginner friendly) n = int(value) if n % 2 != 0: do_stuff(n) ``` ```python numbers = [1, 10, 42] k = random.randrange(3) # Don't result = [ (n, k - n) for i, n in enumerate(numbers) if k - n in l[i + 1:] # `k - x` operation has a pure behavior ] # Do result = [ (n, complement) for i, n in enumerate(numbers) if (complement := k - n) in l[i + 1:] ] ``` Be careful not to fall into those other [[Anti-Pattern|anti-patterns]]: - [[Non-scoped Walrus]] - [[Needless temporary variable]] --- Bibliography: - [Title - website.com](need bibliography)