use _build_filters function instead of specifying request params manuall...

...y
Yep probably 0-based indexing also works (?) with EC2 API. However, 1-based indexing is mentioned in all examples in EC2 API reference:

<quote>
https://ec2.amazonaws.com/?Action=DescribeVolumes
&Filter.1.Name=attachment.instance-id
&Filter.1.Value.1=i-1a2b3c4d
&Filter.2.Name=attachment.delete-on-termination
&Filter.2.Value.1=true
&AUTHPARAMS
</quote>