code: func DefaultPrepareTransfers(a *api.API, provider SeedProvider) PrepareTransfersFunc {
  	return func(transfers bundle.Transfers, options api.PrepareTransfersOptions) ([]trinary.Trytes, error) {
  		seed, err := provider.Seed()
  		if err != nil {
  			return nil, err
  		}
  		return a.PrepareTransfers(seed, transfers, options)
  	}
  }
docs: // DefaultPrepareTransfers is the default prepare transfers function used by the account, if non is specified.