code: def namedb_vesting_txid(address, token_type, token_amount, block_height):
      
      preimage = '{} vesting {} {} at {}'.format(address, token_type, token_amount, block_height)
      return virtualchain.lib.hashing.bin_double_sha256(preimage).encode('hex')
docs: Make a "fake" txid for a vesting transaction.
      Returns a 32-byte hash (double-sha256), hex-encoded