Errors found in the control_flow notebook

[despadam]

• Add more examples for one-line syntax.
• Provide multiple solutions: from a simpler one to a more advanced one.
• Add better explanation and more examples for continue and break statements.
• Add a section explaining the complexity that a nested loop adds to the code and how to avoid this.
• In exercise find a pair of numbers:
  • specify that we are looking for the first pair encountered,
  • specify that the two numbers should not be the same,
  • show how to solve this with both a nested and a single loop.

[edoardob90]

Fix:

python-tutorial/tutorial/tests/test_control_flow.py

Line 197 in b2eca0f

cats = {i: False for i in range(1, 101)}

with a simpler

cats = dict.fromkeys(range(1, 101), False)