パラメータ
- c
 - A Unicode character.
 - fullWidth
 - true to return a full width Katakana, and false to return a half width Katakana.
 
戻り値の型
The Katakana equivalent of c.
- or -
The unchanged value of c, if c is already a Katakana or not Hiragana.
The Katakana equivalent of c.
- or -
The unchanged value of c, if c is already a Katakana or not Hiragana.