Solved example 7.7

Circle function in utils.py was also broken
Revert "Solved example 7.7"

This reverts commit b17ea29b23cbcf41c7a81e1036b4f699f03a6d49.
Solved example 7.7
Applied PEP8 to example 7.6
Merge pull request #79 from Fugacity59/master

Solved Example 7.7