code: def electrum_prv(self, s):
          
          blob = self._electrum_to_blob(s)
          if blob and len(blob) == 32:
              mpk = from_bytes_32(blob)
              return self._network.keys.electrum_private(master_private_key=mpk)
docs: Parse an electrum private key from a text string in seed form ("E:xxx" where xxx
          is a 64-character hex string).
          Return a :class:`ElectrumWallet <pycoin.key.electrum.ElectrumWallet>` or None.