Memoization with Dicts

Memoization is caching the results of expensive function calls. When the function is called again with the same arguments, you return the cached result instead of recomputing. This can dramatically improve performance for functions called repeatedly with the same inputs. The name comes from "memo" as in memorandum - you are writing down results for future reference. Data engineers use memoization constantly. Looking up dimension data, parsing configuration, validating schemas - these operations are often repeated with identical inputs. Caching avoids redundant database queries, file reads, or computations. A function that takes 100ms to query a database can return instantly on subsequent calls with the same parameters. The key insight is that pure functions - functions that always return t