void processInput(char *input, int row, int column) {
    printf("\n**process input**\n");
    Cell *cell = cells[row][column];
    free(cell->input); // free old input
    cell->input = strdup(input); // copy input string
    printf("cell->input: %s (row %d, column %d) (strlen = %d)\n",
    cell->input, row, column, (int)strlen(input));

    guiSetInput(input, row, column);


    //Remove current cell from the listeners list in all cells in the listeningTo list of the current cell
    Node *node = cell->listeningTo->first;
//    printf("\t%d\t%d listening to %s will be removed\n", row, column, toCString(cell->listeningTo)); Debug
    for (; node != NULL; node = node->next) {
        Cell *curCell = (Cell*)node->value;
        removeObject(cell->listeners, curCell);
    }

    removeAll(cell->listeningTo);

    //Set new references
    references(cell->listeningTo, parse(newString(cell->input)));
    printf("\(%d\t%d) listening to %s\n", row, column, toCString(cell->listeningTo));
    node = cell->listeningTo->first;
    for (; node != NULL; node = node->next) {
        Cell *curCell = (Cell*)node->value;
        if (contains(curCell->listeners, cell) == 0) {
            append(curCell->listeners, cell);
        }
        printf("\t(%d\t%d) has listeners  %s\n", curCell->row, curCell->column, toCString(curCell->listeners));
    }

    //Evaluate
    Object *evalResult = evaluate(parse(newString(cell->input)));
    cell->value = evalResult;
    char *result = "";
    if (evalResult != NULL) {
        result = toCString(evalResult);
    } else {
        result = "Could not Evaluate Input";
    }

    guiSetOutput(result, row, column);

    updateReferencedCells(cell);

    saveFile(currentFileName);
}