Typo: '...code that *can* be mixed into other objects...'
Typo: '...look back at *a* previous example...'
Style: `yield()` instead of 'yield'
Typo: '...a more...' instead of '...amore...'
Typo: '...a few *different* possibilities...'
Typo: '...allows you to *execute* basic *nix file operations...'
Merge pull request #2 from d1/fix-typos

Fix typos