Done with day2 assignments

Here you need to write the method sum_of_arr which perform addition of elements in array and return the sum.

Here is skeleton of code:
<pre>
def sum_of_arr(arr)
    arr.each do |x|
        ....# think how you will use this x to get its sum
    end 
    ..... # Obviously you need to return sum here.  
end

a = [1, 2, 3, 4, 5]
sum = sum_of_arr(a)
puts "Sum: #{sum}"
</pre>