code: func (c *Client) Issue(tokensToIssue []*token.TokenToIssue) ([]byte, error) {
  	serializedTokenTx, err := c.Prover.RequestImport(tokensToIssue, c.SigningIdentity)
  	if err != nil {
  		return nil, err
  	}
  
  	tx, err := c.createTx(serializedTokenTx)
  	if err != nil {
  		return nil, err
  	}
  
  	return tx, c.TxSubmitter.Submit(tx)
  }
docs: // Issue is the function that the client calls to introduce tokens into the system.
  // Issue takes as parameter an array of token.TokenToIssue that define what tokens
  // are going to be introduced.