Improve conditional 'if'

'nil' evaluates 'false' for 'if' conditionals
Remove nested if. The 'and' operator for the rescue.
Change for the oneline version.

Now it's so cute! :-)
Take advantage of the fact that nil evaluates to false

We just need to reverse the order of the 'if' 'else' clause.
Remove unecessary return

Now that this is the last expression evaluated, it will "return" by default.
Sleep while waiting with @curs.alive?

This reads better (for me) and saves cpu time.

And... perhaps with a better code structure it's possible to completely get rid of this "waiting" thing.
Remove unecessary return
Reverse 'if/else' clause because 'nil' evaluates to false
Remove 'else false' because 'if' returns 'nil' if not satisfied
Add redundant code just for preparing for next commit
Add more concise, readable and ruby idiomatic way
DRY code using SpinningBlock#alive?
Removes negation of negation at 'if' clause
Change for the online form of the 'raise'
Fix indentation
Prepare for next commit
Use 'unless' instead of 'if not'
Use oneline version of 'unless'
Remove unecessary 'return'
DRY code removing unecessary 'else' for repeating ending code