Calculates the working time elapsed between two dates. Depending on the business, hours vary.

To add a new business and its particular hours, you must:

1. Define a module with the name of the business.
2. Implement the Time.PWorkingTimeForBusiness protocol, to define particular hours. Use the following template:

```
define Time.PWorkingTimeForBusiness, for: Atom do
    def function_name(date, <business_name>) do
        ...
    end

    ...

end
```

parameter

Parameter:

- start_date: Timex.DateTime or String. Start date.

- end_date: Timex.DateTime or String. End date.

- business: Atom. Business.

- change_timezone: Boolean. Indicate if you have to change the dates to the time use defined in the configuration.

return

Return:

- {:ok, integer} | {:error, string}