After following the Book of Programming Bitcoin by O'Reilly.
Exercise 9 of chapter 4, suggest to try send and receive coins.
During my test to access the faucet was no luck, the page hung.
Therefore i googled and found this testnet server with docker.
Also a tool for aid to check and validate your WIF (Wallet Import Format)
and a picture to describe about WIF, Private Key and Public Key.
"error code: -4
the wallet1 begin to has balance.
to bech32 address and to legacy address.
not be seen, unless one transfer/send-fund to the legacy address
earlier in #bitcoin-cli section
to connect to the container
exactly as the fund send to the legacy-address
notice the label is empty string ""
into another wallet