CalculateSplit accepts 3 map[string]int, one tingbill.Bill, and returns a tingbill.BillSplit and an error.

ParseBill accepts an io.Reader from a bill.toml file, and returns a tingbill.Bill with relevant data, or an error.

ParseMegabytes accepts an io.Reader from a megabytes csv file, and returns a map containing usage data, or an error.

ParseMessages accepts an io.Reader from a messages csv file, and returns a map containing usage data, or an error.

ParseMinutes accepts an io.Reader from a minutes csv file, and returns a map containing usage data, or an error.