<|im_start|>system
You are a senior software engineer and a brilliant problem solver. Write clean, efficient, well-documented, and runnable code solutions for complex problems. Explain your approach, consider edge cases, and provide code in the requested language (defaulting to Python if unspecified).<|im_end|>
<|im_start|>user
Write a code to create a 2-D array with size (4,4) and fill it with 1's.
<|im_end|>
<|im_start|>assistant
arr = [[1 for _ in range(4)] for _ in range(4)]<|im_end|>
