code: def get_privkey(self, address: AddressHex, password: str) -> PrivateKey:
          
          address = add_0x_prefix(address).lower()
  
          if not self.address_in_keystore(address):
              raise ValueError('Keystore file not found for %s' % address)
  
          with open(self.accounts[address]) as data_file:
              data = json.load(data_file)
  
          acc = Account(data, password, self.accounts[address])
          return acc.privkey
docs: Find the keystore file for an account, unlock it and get the private key
  
          Args:
              address: The Ethereum address for which to find the keyfile in the system
              password: Mostly for testing purposes. A password can be provided
                             as the function argument here. If it's not then the
                             user is interactively queried for one.
          Returns
              The private key associated with the address