Write a function, max_value, that takes in list of numbers as an argument. The function should return the largest number in the list.

Solve this without using any built-in list methods.

You can assume that the list is non-empty.

max_value([4, 7, 2, 8, 10, 9])

max_value([10, 5, 40, 40.3])

max_value([-5, -2, -1, -11])

max_value([42])

max_value([1000, 8])

max_value([1000, 8, 9000])

max_value([2, 5, 1, 1, 4])