vo = und;
nl = und; 
// Type 'undefined' is not assignable to type 'null'.
nev = und; 
// Type 'undefined' is not assignable to type 'never'.

a = nl;
unk = nl;
obj = nl; 
// Type 'null' is not assignable to type ‘{}’.
vo = nl;  
// Type 'null' is not assignable to type 'void'.
und = nl; 
// Type 'null' is not assignable to type 'undefined'.
nev = nl; 
// Type 'null' is not assignable to type 'never'.

a = nev;
unk = nev;
obj = nev;
vo = nev;
und = nev;
nl = nev;