text: 'use strict';
  
  const org = 'HowProgrammingWorks';
  
  // delete org; // Raises SyntaxError on strict mode
  
  const country = {
    name: 'Chile',
    ruler: 'Augusto Pinochet',
    born: 1915,
    alive: false
  };
  
  delete country.ruler;
  console.dir({ country });
  
  delete country.born;
  delete country.population;
  console.dir({ country });
  
  const currencies = ['BTC', 'EUR', 'UAH', 'BSD'];
  
  console.log('currencies[1]:', currencies[1], 1 in currencies);
  console.log('currencies[2]:', currencies[2], 2 in currencies);
  
  delete currencies[1];
  currencies[2] = undefined;
  console.dir({ currencies });
  
  console.log('currencies[1]:', currencies[1], 1 in currencies);
  console.log('currencies[2]:', currencies[2], 2 in currencies);
  