Interface for filling multi-dimensional histograms
Consider the following snippet.
Gaudi::Accumulators::Histogram<2> m_gaussVflat{
this, "GaussFlat", "Gaussian V Flat, atomic", { { 50, -5, 5, "X" }, { 50, -5, 5, "Y" } } };
++m_gaussVflat[ {flat, gauss} ]; // expected usage
++m_gaussVflat[ gauss ]; // this compiles, but what does it do?