This question evaluates a candidate's skills in text processing, large-scale I/O, token normalization, memory-constrained computation and algorithmic trade-offs for frequency aggregation, and it falls under the Coding & Algorithms domain because it combines parsing, data structures and external processing concerns.
Write a function that reads a large text file and returns the frequency count of each word. Define how you will normalize tokens (case, Unicode, punctuation, contractions), handle memory limits (streaming, chunking), and output the top-k most frequent words efficiently. Analyze time and space complexity and discuss trade-offs between hash maps, tries, and external sorting when the file barely fits in memory.