System.Dynamic.BindingRestrictions.InstanceRestriction.GetExpression C# (CSharp) Method

            internal override Expression GetExpression()
            {
                if (_instance == null)
                {
                    return Expression.Equal(
                        Expression.Convert(_expression, typeof(object)),
                        AstUtils.Null
                    );
                }

                ParameterExpression temp = Expression.Parameter(typeof(object), null);
                return Expression.Block(
                    new TrueReadOnlyCollection<ParameterExpression>(temp),
                    new TrueReadOnlyCollection<Expression>(
#if ENABLEDYNAMICPROGRAMMING
                        Expression.Assign(
                            temp,
                            Expression.Property(
                                Expression.Constant(new WeakReference(_instance)),
                                typeof(WeakReference).GetProperty("Target")
                            )
                        ),
#else
                        Expression.Assign(
                            temp,
                            Expression.Constant(_instance, typeof(object))
                        ),
#endif
                        Expression.AndAlso(
                            //check that WeakReference was not collected.
                            Expression.NotEqual(temp, AstUtils.Null),
                            Expression.Equal(
                                Expression.Convert(_expression, typeof(object)),
                                temp
                            )
                        )
                    )
                );
            }
        }