  def GetDisk(
      self,
      disk_name: str,
      resource_group_name: Optional[str] = None) -> 'AZComputeDisk':
    """Get disk from AZ subscription / resource group.

    Args:
      disk_name (str): The disk name.
      resource_group_name (str): Optional. The resource group name to look
          the disk in. If none specified, then the disk will be fetched from
          the AZ subscription.

    Returns:
      AZComputeDisk: An Azure Compute Disk object.

    Raises:
      ResourceNotFoundError: If the disk was not found in the subscription/
          resource group.
    """
    disks = self.ListDisks(resource_group_name=resource_group_name)
    if disk_name not in disks:
      raise errors.ResourceNotFoundError(
          'Disk {0:s} was not found in subscription {1:s}'.format(
              disk_name, self.az_account.subscription_id), __name__)
    return disks[disk_name]
Get disk from AZ subscription / resource group.

Args:
disk_name (str): The disk name.
resource_group_name (str): Optional. The resource group name to look
the disk in. If none specified, then the disk will be fetched from
the AZ subscription.

Returns:
AZComputeDisk: An Azure Compute Disk object.

Raises:
ResourceNotFoundError: If the disk was not found in the subscription/
resource group.
libcloudforensics/providers/azure/internal/compute.py