Fix whitespace not conforming to code style in some examples.

In the examples about not using magic numbers, the if statements don’t (but should) conform to the code style advocated further down in the guide.

Status: **Ready to merge**

Reviewers: @jansepar 
Ticket: N/A
Linked PRs: N/A

## Changes
- In examples not demonstrating bad style, fix missing space between `if` and opening parens.