leetcode problem

class Solution:
    def twoSum(self, nums: list[int], target: int) -> list[int]:
        # We try to use a dictionary to map numbers to their index
        seen = {}

        for i, num in enumerate(nums):
            # Bug 1 & 2: Math and logic error here
            complement = num - target

            # Bug 3: Checking the wrong dictionary state
            if complement in seen():
                return [seen[complement], i]

            # Bug 4: Storing the wrong key-value relationship
            seen[i] = num

        # Bug 5: Missing fallback return statement