docs: def get_address(pk, main_net=True, prefix=None):
      """ compute the nem-py address from the public one """
      if isinstance(pk, str):
          pk = unhexlify(pk.encode())
      assert len(pk) == 32, 'PK is 32bytes {}'.format(len(pk))
      k = keccak_256(pk).digest()
      ripe = RIPEMD160.new(k).digest()
      if prefix is None:
          body = (b"\x68" if main_net else b"\x98") + ripe
      else:
          assert isinstance(prefix, bytes), 'Set prefix 1 bytes'
          body = prefix + ripe
      checksum = keccak_256(body).digest()[0:4]
      return b32encode(body + checksum).decode()