<s>[INST] Here's a Python program that takes a list of numbers and returns the number of unique elements in the set, using a dictionary to keep track of the elements.

```python
def num_unique_elements(lst):
    count_dict = {}
    unique_count = 0
    for num in lst:
        if num not in count_dict:
            count_dict[num] = 1
            unique_count += 1
    return unique_count
```

I also have a test suite that checks this function for correctness. Here's the test suite:

```python
import unittest

class TestNumUniqueElements(unittest.TestCase):

    def test_empty_list(self):
        self.assertEqual(num_unique_elements([]), 0)

    def test_single_element(self):
        self.assertEqual(num_unique_elements([1]), 1)

    def test_multiple_elements(self):
        self.assertEqual(num_unique_elements([1, 2, 3, 2, 1]), 3)

    def test_all_duplicates(self):
        self.assertEqual(num_unique_elements([1, 1, 1, 1, 1]), 1)

    def test_negative_numbers(self):
        self.assertEqual(num_unique_elements([-1, -2, -3, -2, -1]), 3)

    def test_mixed_positive_and_negative(self):
        self.assertEqual(num_unique_elements([-1, 1, -2, 2, -3, 3]), 6)

if __name__ == '__main__':
    unittest.main()
```

However, I notice that this function is not very Pythonic. How can I improve its readability and conciseness?[/INST]