code: func (c *BoundContract) Transact(opts *TransactOpts, method string, params ...interface{}) (*types.Transaction, error) {
  	// Otherwise pack up the parameters and invoke the contract
  	input, err := c.abi.Pack(method, params...)
  	if err != nil {
  		return nil, err
  	}
  	return c.transact(opts, &c.address, input)
  }
docs: // Transact invokes the (paid) contract method with params as input values.