function L = graph_arc_twig ( )

%*****************************************************************************80
%
%% graph_arc_twig() sets up the arc list for the twig graph.
%
%  Discussion:
%
%    The graph has 3 nodes.
%    The graph has 2 edges or 4 arcs.
%
%    1---2---3
%
%  Licensing:
%
%    This code is distributed under the MIT license. 
%
%  Modified:
%
%    30 April 2026
%
%  Author:
%
%    John Burkardt
%
%  Output:
%
%    integer L[arc_num,2]: the arc list.
%
  L = [ ...
    1, 2; ...
    2, 1; ...
    2, 3; ...
    3, 2 ];

  return
end
