Write a function psum(L) which for a list of numbers L returns the list of partial sums. By this we mean the list [L[0], L[0] + L[1], L[0] + L[1] + L[2], ...]. The last value in the resulting list will be the sum of all values in the list L. For example, if L = [1, 2, 3] then the resulting list will be [1, 3, 6]. Use the docstring """Returns the list of partial sums""". Do not change the main program. Expected output: [1, 3, 6, 10, 15, 21, 28, 36, 45, 55]