"""Demo script for users: contains several detectable anti-patterns.

- membership test against a list inside a loop  -> membership_in_list
- nested loops                                  -> nested_loops
- string concatenation with += inside a loop    -> str_concat_loop
"""


def build_report(rows, allow):
    out = ""
    for r in rows:
        if r in allow:            # O(n) membership test on a list
            out += str(r) + ","   # string += accumulation
        for other in rows:        # nested loop -> O(n^2)
            if r == other:
                pass
    return out


def main():
    rows = list(range(400))
    allow = list(range(0, 400, 2))
    for _ in range(30):
        build_report(rows, allow)


main()