Function fetch_signers 

pub fn fetch_signers(
    base: &str,
    credential: &Credential,
) -> Result<Signers, String>

GET /api/signers on the home at base, checked: every key’s id is the hash of the key it is listed beside, and the node’s too.

Errors

The home cannot be reached, refuses the grant, or serves a body this build does not read.