code: def add_filepath(self, manifest, filepath, fullpath, copy=False):
          
          filepath = os.path.normpath(filepath)
          if self.manifests[manifest].add_filepath(filepath, fullpath, copy):
              # Only link if filepath was added
              self.manifests[manifest].make_link(filepath)
docs: Wrapper to the add_filepath function in PayuManifest. Prevents outside
          code from directly calling anything in PayuManifest.