Suppose I have the following spec:

```
describe Thing do
  it 'can read data' do
    @data = get_data_from_file  # [ '42', '36' ]
    expect(@data.count).to eq 2
  end

  it 'can process data' do
    expect(@data[0].to_i).to eq 42  # Fails because @data is nil
  end
end

```

All I wanted is to have a variable shared in the given *describe* or *context*. I would write a value in one example and read it in another. How do I do that?