I'm wondering why I cannot simply cast the return result of .get() to
satisfy the compiler expectation that the method return an object.
Instead I have to  assign the result of .get() to a variable and then
return that.

package redick;

import java.util.*;
import java.util.Iterator;

public class Environment {
    /*
    * map from a variable name to an Object - which may be a datum or a
    * procedure
    */
    public Map<String,Object> bindings = new HashMap<String, Object>();
    public Environment parent;

    public void put(String var, Object value) {
        bindings.put(var, value);
    }
    public Object get(String var) {

        Object retval = bindings.get(var); // cast not enough
        /* Cannot comment this section out */
        if (retval == null) {
            return (Object)null;
        } else {
            return retval;
        }
        /* End required section */
    }

    public String toString() { return bindings.toString(); }

}