Simplify str.find explaination as per Georg Brandl's suggestion.
.. method:: str.find(sub[, start[, end]])
- Return the lowest index in the string where substring *sub* is found, such
- that *sub* is contained in the slice ``s[start:end]``. Optional arguments
- *start* and *end* are interpreted as in slice notation. Return ``-1`` if
- *sub* is not found.
+ Return the lowest index in the string where substring *sub* is found within
+ the slice ``s[start:end]``. Optional arguments *start* and *end* are
+ interpreted as in slice notation. Return ``-1`` if *sub* is not found.
.. note::