code: function makeQueryString(obj, prefix='') {
  	const str = [];
  	let prop;
  	let key;
  	let value;
  
  	for (prop in obj) {
  		if (obj.hasOwnProperty(prop)) {
  			key = prefix ?
  				prefix + '[' + prop + ']' :
  				prop;
  			value = obj[prop];
  			str.push(typeof value === 'object' ?
  				makeQueryString(value, key) :
  				encodeURIComponent(key) + '=' + encodeURIComponent(value));
  		}
  	}
  
  	return str.join('&');
  }
docs: Take a simple object and turn it into a queryString, recursively.
  
  @param {object} obj - query object
  @param {string} prefix - used in recursive calls to keep track of the parent
  @return {string} queryString without the '?''