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Added the code markdown for NSOperation and BTTask
Switched to the newer Objective-C convention of “instancetype” rather than the less-DRY approach used previously.
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Merge pull request #10 from mrplants/master

Switched to the newer Objective-C convention of “instancetype”
Merge pull request #6 from RuiAAPeres/patch-1

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Merge pull request #11 from travisjeffery/fix-code-examples

Fix code examples (fixes #4)
Fix method names with args