Add an entry to an arrow dataset
You should do `combined_dataset = concatenate_datasets([datasets['train'], modified_dataset['train']])`

Didn't we talk about returning a Dataset instead of a DatasetDict with load_dataset and no split provided @lhoestq? Not sure it's the way to go but I'm wondering if it's not simpler for some use-cases.
Is it possible to add an entry to a dataset object?

**Motivation: I want to transform the sentences in the dataset and add them to the original dataset**

For example, say we have the following code:

``` python
from datasets import load_dataset

# Load a dataset and print the first examples in the training set
squad_dataset = load_dataset('squad')
print(squad_dataset['train'][0])
```

Is it possible to add an entry to `squad_dataset`? Something like the following?

``` python
squad_dataset.append({'text': "This is a new sentence"})
```

The motivation for doing this is that I want to transform the sentences in the squad dataset and add them to the original dataset.

If the above doesn't work, is there any other way of achieving the motivation mentioned above? Perhaps by creating a new arrow dataset by using the older one and the transformer sentences?

Add an entry to an arrow dataset 
 Is it possible to add an entry to a dataset object?

**Motivation: I want to transform the sentences in the dataset and add them to the original dataset**

For example, say we have the following code:

``` python
from datasets import load_dataset

# Load a dataset and print the first examples in the training set
squad_dataset = load_dataset('squad')
print(squad_dataset['train'][0])
```

Is it possible to add an entry to `squad_dataset`? Something like the following?

``` python
squad_dataset.append({'text': "This is a new sentence"})
```

The motivation for doing this is that I want to transform the sentences in the squad dataset and add them to the original dataset.

If the above doesn't work, is there any other way of achieving the motivation mentioned above? Perhaps by creating a new arrow dataset by using the older one and the transformer sentences?
 
 You should do `combined_dataset = concatenate_datasets([datasets['train'], modified_dataset['train']])`

Didn't we talk about returning a Dataset instead of a DatasetDict with load_dataset and no split provided @lhoestq? Not sure it's the way to go but I'm wondering if it's not simpler for some use-cases.