how to make a negativ loop in lua code example

Example 1: lua for loop

-- For K,V in table
for k,v in pairs(tbl) do
 print(k)
 print(v)
end
-- For i=0, num
for i=0, num do
 print(i)  
end

Example 2: For loop lua

for startValue, EndValue, [increments] do
        --code to execute
end
--The increments value is optional.  If it isn't defined, it is assumed to be "1"