Your question is Custom Stack Implementation. Start with the requirements on the right.
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How would you implement a custom Stack using basic array structures? What corner cases must you account for?
Implement process_stack(capacity, operations) using a fixed-size Python list, without relying on Python list methods such as append() or pop() for stack behavior. Each operation is ['push', value], ['pop'], ['peek'], or ['size']; return one result per operation: True or False for pushes, the removed or viewed value for pop and peek, None when those operations target an empty stack, and the current integer size for size.
def process_stack(capacity, operations):