Write a Python function `overlapping` that checks whether any value in one sequence exists in another sequence. The function should take two sequences as input and return `True` if there is at least one common element between them, otherwise return `False`.
#### Example Usage
```python [main.nopy]
print(overlapping([1, 2, 3, 4, 5], [6, 7, 8, 9])) # Output: False
print(overlapping([1, 2, 3], [3, 4, 5])) # Output: True
print(overlapping(['a', 'b'], ['c', 'd', 'a'])) # Output: True
```
#### Requirements
- The function should work for sequences of any type (e.g., lists, tuples).
- The function should return a boolean value.
- Avoid using built-in set operations for this challenge.