Given the function testy below, what is drawn with the following calls?
>> testy
>> testy(7)
>> testy(10,20)

function testy(x,y)
  if (nargin==0)
      plot(1:5,1:5,'k*-');
  elseif (nargin==1)
        plot(1:x, 1:x, 'r*-');
  elseif (nargin==2)
      plot(1:max(x,y),1:max(x,y),'b*-');
  end