1. Write a function that calculates the volume of a sphere using the formula 4/3*pi*r³. What is the volume of a sphere with radius of 5?

Hint 1: The module math has a field called pi.

Hint 2: The answer is not 392.70.

2. Write a function that takes a list as argument and returns a list of unique elements from the original list.

3. Create a dictionary D with keys a, b, and c. What happens if you try to index an nonexistent key d (D[d])? Whath appens if you try to assign a nonexisting key d (e.g. D[d] = 'spam')?

4. Write a for loop that prints a dictionary's items in sorted (ascending) order.

Hint: Use dictionary keys and the list sort method.

5. Write a function, copyDict(dict) that copies a dictionary. It should return a new dictionary with all items in its argument.