function createElement( options, clbk ) {
	var opts;
	var err;
	var cb;
	opts = copy( defaults );
	if ( arguments.length > 1 ) {
		err = validate( opts, options );
		if ( err ) {
			throw err;
		}
		cb = clbk;
	} else {
		cb = options;
	}
	if ( !isFunction( cb ) ) {
		throw new TypeError( format( 'invalid argument. Last argument must be a function. Value: `%s`.', cb ) );
	}
	tex2svg( opts.raw, done );

	/**
	* Callback invoked upon rendering an equation as SVG.
	*
	* @private
	* @param {(Error|null)} error - error object
	* @param {string} svg - SVG string
	* @returns {void}
	*/
	function done( error, svg ) {
		if ( error ) {
			return cb( error );
		}
		cb( null, render( opts, svg ) );
	}
}
Generates an HTML string for inlining an SVG equation in Markdown.

@param {Options} [options] - function options
@param {string} [options.className='equation'] - element class name
@param {string} [options.align='center'] - element alignment
@param {string} [options.raw] - raw equation text
@param {string} [options.label] - equation label
@param {Callback} clbk - callback to invoke upon completion
@throws {TypeError} options argument must be an object
@throws {TypeError} must provide valid options
@throws {TypeError} last argument must be a function

@example
var opts = {
    'className': 'equation',
    'align': 'center',
    'raw': '\\operatorname{erf}(x) = \\frac{2}{\\sqrt\\pi}\\int_0^x e^{-t^2}\\,\\mathrm dt'
    'label': 'eqn:erf'
};
createElement( opts, done );

function done( error, out ) {
    if ( error ) {
        throw error;
    }
    console.log( out );
}