code: function( version ) {
  
      version = version || '4.0'
  
      var keys = Object.keys( this.data )
      var data = [ [ 'version', {}, 'text', version ] ]
      var prop = null
  
      for( var i = 0; i < keys.length; i++ ) {
        if( keys[i] === 'version' ) continue;
        prop = this.data[ keys[i] ]
        if( Array.isArray( prop ) ) {
          for( var k = 0; k < prop.length; k++ ) {
            data.push( prop[k].toJSON() )
          }
        } else {
          data.push( prop.toJSON() )
        }
      }
  
      return [ 'vcard', data ]
  
    }
docs: Format the card as jCard
  @param {String} version='4.0'
  @return {Array} jCard