After installing the package using devtools::install_github, the following error arose:
> my_friend = NetworkDataCompanion::CreateNetworkDataCompanionObject()
Error in CreateTCGAPurityFilteringObject() :
could not find function "CreateTCGAPurityFilteringObject"
The problem is solved by loading the TCGAPurityFiltering library directly, but this is a namespace issue that should be corrected in the repo so the user does not have to do this.