def mytotal( ds ):
   "returns the total of every element in the dataset that is greater than 10."
   r= where( ds.gt(10) )
   return total( ds[r] )


def ellipsis( xwidth, ywidth ):
    t= linspace( 0, TAU, 361 )
    x= cos( t ) * xwidth
    y= sin( t ) * ywidth
    
    return link( x, y )