Write a function `toggle_case` that takes a string as input and returns a new string where the case of each character is toggled. Uppercase characters should become lowercase, and lowercase characters should become uppercase.
#### Example Usage
```python [main.nopy]
print(toggle_case("Python")) # Output: "pYTHON"
print(toggle_case("Pangram")) # Output: "pANGRAM"
print(toggle_case("LIttLE")) # Output: "liTTle"
```
#### Constraints
- The input string will only contain alphabetic characters.
- The function should handle both uppercase and lowercase letters.