tr

Returns a copy of str with the characters in from_str replaced by the corresponding characters in to_str. If to_str is shorter than from_str, it is padded with its last character. Both strings may use the c1–c2 notation to denote ranges of characters, and from_str may start with a ^, which denotes all characters except those listed.

"hello".tr('aeiou', '*')    #=> "h*ll*"
"hello".tr('^aeiou', '*')   #=> "*e**o"
"hello".tr('el', 'ip')      #=> "hippo"
"hello".tr('a-y', 'b-z')    #=> "ifmmp"