function sendFungibleTokens(
  denomination: string,
  amount: uint256,
  sender: string,
  receiver: string,
  sourcePort: string,
  sourceChannel: string,
  timeoutHeight: Height,
  timeoutTimestamp: uint64): uint64 {
    prefix = "{sourcePort}/{sourceChannel}/"
    // we are the source if the denomination is not prefixed
    source = denomination.slice(0, len(prefix)) !== prefix
    if source {
      // determine escrow account
      escrowAccount = channelEscrowAddresses[sourceChannel]
      // escrow source tokens (assumed to fail if balance insufficient)
      bank.TransferCoins(sender, escrowAccount, denomination, amount)
    } else {
      // receiver is source chain, burn vouchers
      bank.BurnCoins(sender, denomination, amount)
    }

    // create FungibleTokenPacket data
    data = FungibleTokenPacketData{denomination, amount, sender, receiver}

    // send packet using the interface defined in ICS4
    sequence = handler.sendPacket(
      getCapability("port"),
      sourcePort,
      sourceChannel,
      timeoutHeight,
      timeoutTimestamp,
      data
    )

    return sequence
}