Auxiliary C Code ...
TOKEN makeif(tok, exp, thenpart, elsepart)
TOKEN tok, exp, thenpart, elsepart;
{ tok-> tokentype = OPERATOR; /* change tok */
tok-> whichval = IFOP; /* to if op */
if (elsepart != NULL)
elsepart-> link = NULL;
thenpart-> link = elsepart;
exp-> link = thenpart;
tok-> operands = exp;
return tok;
}