group of transparent objects tikz

if you have a group of overlaying objects and want them to be transparent, a standard procedure is that you set the transparency for each object.
But this may lead to a overlap of these transparent object and that you see the underlying whereas you actually just want to have the full combined object transparent.

You can simply solve that by placing the group of objects in a scope and set the group properties to transparent in the following way:

\begin{scope}[transparency group, opacity=0.5]
% group of objects
% more objects
\end{scope}