Find the sum of the natural numbers from 6 to 21
6 21 1 [OP_LIST_ARANGE] [OP_LIST_SUM]
var_a = 6
var_b = 21
var_c = 1
list_a = [i for i in range(var_a, var_b + 1, var_c)]
list_a = [float(i) for i in list_a]
var_d = sum(list_a)
print(int(var_d))