(4 kyu) Sum Strings as Numbers.md

Sum Strings as Numbers (4 kyu)

https://www.codewars.com/kata/5324945e2ece5e1f32000370

Given the string representations of two integers, return the string representation of the sum of those integers.

For example:

sumStrings('1','2') // => '3'

A string representation of an integer will contain no characters besides the ten numerals "0" to "9".