RHRVEasyResultObject: An object of class RHRVEasyResult as returned by RHRVEasy()
saveHRVIndicesInPath: The path where the HRV indices will be saved as an excel file. The name of the file is automatically created based on the groups being compared.
filename: Filename of the excel file. If not provided, the name of the file is built using the names of the groups being compared.