def METHOD_NAME(testerchain):
    # Manually create a TransactingPower
    eth_address = testerchain.etherbase_account
    power = TransactingPower(password=INSECURE_DEVELOPMENT_PASSWORD,
                             signer=Web3Signer(testerchain.client),
                             account=eth_address)
    # Manually unlock
    power.unlock(password=INSECURE_DEVELOPMENT_PASSWORD)
    # Sign
    data_to_sign = b'Premium Select Luxury Pencil Holder'
    signature = power.sign_message(message=data_to_sign)
    # Verify
    is_verified = verify_eip_191(address=eth_address, message=data_to_sign, signature=signature)
    assert is_verified is True
    # Test invalid address/pubkey pair
    is_verified = verify_eip_191(address=testerchain.client.accounts[1],
                                 message=data_to_sign,
                                 signature=signature)
    assert is_verified is False