text: export function isArray(variable) {
    return variable instanceof Array;
  }
  
  export function isDefined(variable){
    return typeof variable !== 'undefined' && variable !== null;
  }
  
  export function isFunction(variable) {
    return typeof variable === 'function';
  }
  
  export function isObject(variable){
    return isDefined(variable) && typeof variable === 'object';
  }