ASR: Support unsigned int unary add

Author: ubaidsk

src/lpython/semantics/python_ast_to_asr.cpp

@@ -3523,6 +3523,12 @@ class CommonVisitor : public AST::BaseVisitor<Struct> {
                                             ASRUtils::expr_value(operand))->m_n;
                     tmp = ASR::make_IntegerConstant_t(al, x.base.base.loc, op_value, operand_type);
                 }
+            } else if (ASRUtils::is_unsigned_integer(*operand_type)) {
+                if (ASRUtils::expr_value(operand) != nullptr) {
+                    int64_t op_value = ASR::down_cast<ASR::UnsignedIntegerConstant_t>(
+                                            ASRUtils::expr_value(operand))->m_n;
+                    tmp = ASR::make_UnsignedIntegerConstant_t(al, x.base.base.loc, op_value, operand_type);
+                }
             } else if (ASRUtils::is_real(*operand_type)) {
                 if (ASRUtils::expr_value(operand) != nullptr) {
                     double op_value = ASR::down_cast<ASR::RealConstant_t>(