anchor.diff:      true;
   is_between(_, plus_infinity, plus_infinity) ->
       true;
  +is_between(minus_infinity, _, plus_infinity) ->
  +    true;
  +is_between(X, minus_infinity, plus_infinity) ->
  +    false;
   is_between(X, Y, plus_infinity) ->
       X =< Y;
   is_between(minus_infinity, minus_infinity, _) ->
  
positive.code:     end.
  
  % @private
  is_covered_helper(#interval2{first=First, last=Last}, _) when First >= Last ->
      true;
  is_covered_helper(Interval, Intervals) ->
      %io:format("helper: ~p ~p~n", [Interval, Intervals]),
      %io:format("find_start: ~p~n", [find_start(Interval#interval2.first, Intervals, [])]),
  
negative.code: 	true -> 
  	    (Begin =< Id) or (Id =< End)
      end.
  
  greater_equals_than(minus_infinity, minus_infinity) ->
      true;
  greater_equals_than(minus_infinity, X) ->
      false;
  greater_equals_than(plus_infinity, plus_infinity) ->
      true;
  greater_equals_than(X, plus_infinity) ->
      false;
  greater_equals_than(X, Y) ->
      X >= Y.
  