Given a post object, returns an array of float coordinates representing
the geographic location saved for that post, or `undefined` if the value
cannot be determined.

@param  {Object} post Post object
@return {string}      Array of geographic float coordinates
function( post ) {
		let latitude, longitude;

		if ( ! post ) {
			return;
		}

		latitude = parseFloat( getValueByKey( post.metadata, 'geo_latitude' ) );
		longitude = parseFloat( getValueByKey( post.metadata, 'geo_longitude' ) );

		if ( latitude && longitude ) {
			return [ latitude, longitude ];
		}
	}