Implement a Matlab function that calculates the color histogram of an image.

function hist_im = MAPII_hist_im(im)
%
% MAPII_hist_im - color histogram of image
% On input:
%     im (mxnx3 rgb image): image
% On output:
%     hist_im (px4 int array): histogram where each row gives r,g,b combo and count
% Call:
%     h3 = MAPII_hist_im(map3);
% Author:
%     Your Name
%     UU
%     Fall 2012
%