[boost] [histogram] Working with standard algorithms

I would like to see a better integration between boost.histogram and standard algorithms, especially those from <numeric>. Today they do not work together because the dereference operator of the axis iterator returns a pair (index and content) rather than the content. An example of where standard algorithms could be useful is calculating the cumulative distribution of a one-dimensional histogram, which ought to be a simple as: auto& axis = h.axis(); std:partial_sum(axis.begin(), axis.end(), axis.begin()); Another example is ranking a set of histograms based on the cosine similarity [1] using std::inner_product(). [1] https://en.wikipedia.org/wiki/Cosine_similarity