String [] s = new String[0]; //new empty array
s = append(s,"Kostas");
s = append(s,"Nashid");
s = append(s,"Jie Eun");
print(s.length); //should be 3
for(int i=0; i<s.length; i++)
  print(s[i] + ", ");
// should be: Kostas, Nashid, Jie Eun,
s = sort(s);
for(int i=0; i<s.length; i++)
  print(s[i] + ", ");
// should be: Jie Eun, Kostas, Nashid,
s = subset(s,1,2);
print(s.length); //should be 2
for(int i=0; i<s.length; i++)
  print(s[i] + ", ");
// should be: Kostas, Nashid,
s = expand(s,5);
print(s.length); //should be 5
for(int i=0; i<s.length; i++)
  print(s[i] + ", ");
// should be: Kostas, Nashid, null, null, null,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,