System.Linq.Expressions.Expression.GetUserDefinedBinaryOperator C# (CSharp) Method

        private static BinaryExpression GetUserDefinedBinaryOperator(ExpressionType binaryType, string name, Expression left, Expression right, bool liftToNull)
        {
            // try exact match first
            MethodInfo method = GetUserDefinedBinaryOperator(binaryType, left.Type, right.Type, name);
            if (method != null)
            {
                return new MethodBinaryExpression(binaryType, left, right, method.ReturnType, method);
            }
            // try lifted call
            if (left.Type.IsNullableType() && right.Type.IsNullableType())
            {
                Type nnLeftType = left.Type.GetNonNullableType();
                Type nnRightType = right.Type.GetNonNullableType();
                method = GetUserDefinedBinaryOperator(binaryType, nnLeftType, nnRightType, name);
                if (method != null && method.ReturnType.GetTypeInfo().IsValueType && !method.ReturnType.IsNullableType())
                {
                    if (method.ReturnType != typeof(bool) || liftToNull)
                    {
                        return new MethodBinaryExpression(binaryType, left, right, method.ReturnType.GetNullableType(), method);
                    }
                    else
                    {
                        return new MethodBinaryExpression(binaryType, left, right, typeof(bool), method);
                    }
                }
            }
            return null;
        }