def set_graphviz_executables(self, paths):
self.progs = paths<EOL>
This method allows to manually specify the location of the GraphViz executables.

        The argument to this method should be a dictionary where the keys are as follows:

            {'dot': '', 'twopi': '', 'neato': '', 'circo': '', 'fdp': ''}

        and the values are the paths to the corresponding executable, including the name
        of the executable itself.