Substring-kata.md

Substring kata

Screencast: https://www.youtube.com/watch?v=ZrHBVTCbcE0

Implement a function with a signature substring(left, righ, start, stop). The function should return the concatenated string, stripped from the start index until the stop index.

Specification by example

Input               |   Output
"abc", "def", 0, 6      "abcdef"
"abc", "def", 0, 1      "a"
"abc", "def", 0, 3      "abc"
"abc", "def", 2, 3      "c"
"abc", "def", 2, 5      "cde"