Write a function triangular$($a$,$b$)$ which creates a staircase based on the numbers a and b$.$ The top level must only consist of the number a and the last level must consist of all numbers from a to b$.$

For example:

Test Result

triangular$(1,5)$

$1$

$12$

$123$

$1234$

$12345$

Answer:$($penalty regime: $0\%)$