Find max number in an array

max.rb

# Find the maximum
def maximum(arr)
  max_val = arr[0]
  arr.each do |num| 
    if num > max_val
      max_val = num
    end
  end
  max_val
end

# expect it to return 42 below
result = maximum([2, 42, 22, 02])
puts "max of 2, 42, 22, 02 is: #{result}"

# expect it to return nil when empty array is passed in
result = maximum([])
puts "max on empty set is: #{result.inspect}"

result = maximum([-23, 0, -3])
puts "max of -23, 0, -3 is: #{result}"

result = maximum([6])
puts "max of just 6 is: #{result}"