function render( state ) {
	var isDefined;
	var opacity;
	var label;
	var color;
	var props;
	var size;
	var xPos;
	var yPos;
	var out;
	var xi;
	var yi;
	var x;
	var y;
	var i;

	debug( 'Rendering closed circles...' );

	isDefined = state.isDefined;
	opacity = state.opacity;
	label = state.label;
	color = state.color;
	size = state.size;
	xPos = state.xPos;
	yPos = state.yPos;
	x = state.x;
	y = state.y;

	out = [];
	for ( i = 0; i < x.length; i++ ) {
		xi = x[ i ];
		yi = y[ i ];
		if ( !isDefined( xi ) || !isDefined( yi ) ) {
			debug( 'Datum %d is undefined. [%s,%s].', i, xi, yi );
			continue;
		}
		debug( 'Rendering datum %d...', i );
		props = {
			'namespace': 'http://www.w3.org/2000/svg',
			'property': 'closed-circle',
			'className': 'closed-circle',
			'attributes': {
				'cx': xPos( xi ),
				'cy': yPos( yi ),
				'r': size( xi, yi, i ) / 2,
				'stroke': 'none',
				'opacity': opacity( xi, yi, i ),
				'fill': color( xi, yi, i ),
				'data-label': label( xi, yi, i )
			}
		};
		debug( 'Generating a virtual DOM tree (%s) with properties: %s.', ELEMENT, JSON.stringify( props ) );
		out.push( h( ELEMENT, props, [] ) );
	}
	return out;
}
Renders data as a closed circles.

@private
@param {Object} state - state
@returns {Array<VTree>} array of virtual trees