origin code: https://github.com/vadv/gopher-lua-libs/tree/master/strings
local strings = require("strings")
-- strings.split(string, sep)
local result = strings.split("a b c d", " ")
-- Output: { "a", "b", "c", "d" }
-- strings.has_prefix(string, prefix)
local result = strings.has_prefix("abcd", "a")
-- Output: true
-- strings.has_suffix(string, suffix)
local result = strings.has_suffix("abcd", "d")
-- Output: true
-- strings.trim(string, cutset)
local result = strings.trim("abcd", "d")
-- Output: abc
-- strings.contains(string, substring)
local result = strings.contains("abcd", "d")
-- Output: true