Returns the client coinbase address.
none
DATA, 20 bytes - the current coinbase address.
// Request
curl -X POST --data '{"jsonrpc":"2.0","method":"eth_coinbase","params":[],"id":64}'
// Result
{
"id":64,
"jsonrpc": "2.0",
"result": "0xc94770007dda54cF92009BFF0dE90c06F603a09f"
}