Kawa

Return a new string where the letters in str are replaced by their upper-case equivalents.

Return a new string where the letters in str are replaced by their lower-case equivalents.

Return a new string where the letters in str that start a new word are replaced by their title-case equivalents, while non-initial letters are replaced by their lower-case equivalents.

Destructively modify str, replacing the letters by their upper-case equivalents.

Destructively modify str, replacing the letters by their upper-lower equivalents.

Destructively modify str, such that the letters that start a new word are replaced by their title-case equivalents, while non-initial letters are replaced by their lower-case equivalents.