Specifying environment variable names

The only feature I'm missing from this great library is the possibility to specify environment variable names for options. Something like this:

.options({
    option-1: {
        type: 'string',
        description: 'description',
        env: 'OTHER_THAN_OPTION_1'                
    }
})

It is "2. The Explicit Approach" mentioned here.

Saying default: process.env.OTHER_THAN_OPTION_1 is not a good option, because the precedence is:

1. Command line args
2. Env vars
3. Config file/objects
4. Configured defaults

so a config file could override the configured default, which is an environment variable in this case.

An example: an option's name can be generic (e.g. account), because the command (e.g. aws) where the option is used gives some context. But an environment variable named ACCOUNT or MY_PREFIX_ACCOUNT has no context. I don't want to prefix my env var with AWS (e.g. AWS_ACCOUNT), because in the same CLI I have many commands with many options that have nothing to do with AWS.

No file or test is named in the issue. Start by tracing the .options(...) entry point and read the referenced yargs issue #305, then identify how command-line, environment, config, and default values are ordered. Done means an option can declare a distinct environment variable name without losing the stated precedence.