function explode(str, delim)
    assert(type(str) == "string", "Bad argument #1 to 'explode', expected string, got " .. type(str) .. ".")
    assert(type(delim) == "string", "Bad argument #2 to 'explode', expected string, got " .. type(delim) .. ".")
    assert(string.len(delim) == 1, "Function 'explode' only supports single-character delimiters.")

    local strings = { }
    local from = 1
    local tpos = 0
    local dfrom, dto = string.find(str, delim, from)

    while dfrom do
        strings[tpos] = string.sub(str, from, dfrom-1)
        tpos = tpos + 1
        from = dto + 1
        dfrom, dto = string.find(str, delim, from)
    end

    table.insert(strings, string.sub(str, from))

    return strings
end

--Example usage

for i,v in pairs(explode("this#is#a#string", "#")) do
    print(v)
end

--[[
 -Output:
    this
    is
    a
    string
]]

--OR

print(explode("this#is#a#string", "#")[1])

--[[
  -Output:
    is
]]