function next() {
			var raw;
			var err;

			idx += 1;
			raw = RAW.exec( nodes[ idx ].value );
			if ( raw === null ) {
				debug( 'Invalid node: %s', nodes[ idx ].value );
				err = new Error( format( 'invalid node. Equation comments must have valid raw equation text. Node: `%s`.', nodes[ idx ].value ) );
				return done( err );
			}
			raw = raw[ 1 ];
			debug( 'Raw equation: %s', raw );

			tex2svg( raw, onSVG );
		}
Creates the next SVG.

@private
@returns {void}