code: def copy_file(self, path, prefixed_path, source_storage):
          
          # Skip this file if it was already copied earlier
          if prefixed_path in self.copied_files:
              return self.log("Skipping '%s' (already copied earlier)" % path)
          # Delete the target file if needed or break
          if not self.delete_file(path, prefixed_path, source_storage):
              return
          # The full path of the source file
          source_path = source_storage.path(path)
          # Finally start copying
          if self.dry_run:
              self.log("Pretending to copy '%s'" % source_path, level=1)
          else:
              self.log("Copying '%s'" % source_path, level=1)
              with source_storage.open(path) as source_file:
                  self.storage.save(prefixed_path, source_file)
          self.copied_files.append(prefixed_path)
docs: Attempt to copy ``path`` with storage