Create a function that converts dash/underscore delimited words into camel casing. The first word within the output should be capitalized only if the original word was capitalized.
to_camel_case("A-B-C") ➞ "ABC"
to_camel_case("the-stealth-warrior") ➞ "theStealthWarrior"
to_camel_case("The_Stealth_Warrior") ➞ "TheStealthWarrior"
An empty string as input "" should return an empty string.