basic delete works

row.cpp

@@ -29,6 +29,11 @@ Row::Row(const Row &other) {
     }
 }
 
+Row& Row::operator=(Row other) {
+    std::swap(m_columns, other.m_columns);
+    return *this;
+}
+
 void Row::setColumnValue(int col_index, int value) {
     m_columns[col_index] = std::make_unique<ColIntegerValue>(value);
 }