d3.eesur = {}; // sub-namespace to the d3 namespace

d3.eesur.line = function module() { // add a line module

// default variable _values in a closure  
	var w = 400,
		h = 400,
		colour = 'black',
		x1 = 0,
		x2 = 100;

	function exports(_selection) {

		_selection.each(function(_data) {

			var yValue = function (d) {
				return d.value;
			};

			var line = d3.select(this)
				.append('svg')
					.attr({
						width: w,
						height: h,
						class: 'line-example'
					})
				.selectAll('line')
				.data(_data);
			
			line 
				.enter()
				.append('line')
					.attr({
						stroke: colour,
						x1: x1,
						x2: x2,
						y1: yValue,
						y2: yValue
					});

			// update code here
			// line
			
			line 
				.exit()
				.remove();

		});
	}

	// public api – getters and setters at the same time  (will either get a new value or set the default variables)

	exports.w = function(_value) {
		if (!arguments.length) return w;
		w = _value;
		return this;
	};
	exports.h = function(_value) {
		if (!arguments.length) return h;
		h = _value;
		return this;
	};
	exports.colour = function(_value) {
		if (!arguments.length) return colour;
		colour = _value;
		return this;
	};
	exports.x1 = function(_value) {
		if (!arguments.length) return x1;
		x1 = _value;
		return this; 
	};
	exports.x2 = function(_value) {
		if (!arguments.length) return x2;
		x2 = _value;
		return this;
	};

	return exports;

};