code: func (dt *DbfTable) Int64FieldValueByName(row int, fieldName string) (value int64, err error) {
  	valueAsString, err := dt.FieldValueByName(row, fieldName)
  	return strconv.ParseInt(valueAsString, 0, 64)
  }
docs: // Int64FieldValueByName returns the value of a field given row number and name provided as an int64