text: let re;
  // Literal Characters
  re = /hello/;
  re = /hello/i;
  
  // Metacharacter Symbols
  re = /^h/i;           // Must start with
  re = / world$/i;     // Must ends with
  re = /^hello$/i;     // Must begin and end with
  re = /h.llo/i;      // Matches any ONE character
  re = /h*llo/i;      // Matches any character 0 or more times
  re = /gre?a?y/i;    // Optional character
  re = /gre?a?y\?/i;    // Escape character 
  
  
  // String to match
  const str = 'Gray?';
  
  
  // Log Results
  const result = re.exec(str);
  console.log(result);
  
  function reTest(re, str) {
      if (re.test(str)) {
          console.log(`${str} matches ${re.source}`);
      } else {
          console.log(`${str} does NOT match ${re.source}`);
      }
  }
  
  reTest(re, str);