Template: escaping a '-' from a sensor attribute

Hello,
Trying to create a template that can read the value for an attribute that has a ‘-’ in its name.

When reading:

{{ states.sensor.rpi_monitor_pi_1.attributes.drives }}

I get the following output:

{'mnt-usb': {'device': '/dev/sda1', 'mount_pt': '/mnt/usb', 'size_gb': 64, 'used_prcnt': 2}, 'root': {'device': '/dev/root', 'mount_pt': '/', 'size_gb': 16, 'used_prcnt': 22}}

So when reading the following:

{{ states.sensor.rpi_monitor_pi_1.attributes.drives.root.size_gb }}

I get ‘16’ as expected.
However, how to read:

{{ states.sensor.rpi_monitor_pi_1.attributes.drives.mnt-usb.size_gb }}

tried different things, like [“mnt-usb”] or mnt\-usb or mnt\\-usb, but they all fail…

Any idea how to get this working?
Thanks

Try this out in dev tools > template

{## Imitate available variables: ##}
{% set my_test_json = {'mnt-usb': {'device': '/dev/sda1', 'mount_pt': '/mnt/usb', 'size_gb': 64, 'used_prcnt': 2}, 'root': {'device': '/dev/root', 'mount_pt': '/', 'size_gb': 16, 'used_prcnt': 22}} %}

{{ my_test_json['mnt-usb']['size_gb'] }}
{{ state_attr('sensor.rpi_monitor_pi_1', 'drives')['mnt-usb']['size_gb'] }}

Thanks @Troon @vingerha
That was the trick!