code: def begin_write(self, content_type=None):
          
          assert not self.is_collection
          if self.provider.readonly:
              raise DAVError(HTTP_FORBIDDEN)
          # _logger.debug("begin_write: {}, {}".format(self._file_path, "wb"))
          # GC issue 57: always store as binary
          return open(self._file_path, "wb", BUFFER_SIZE)
docs: Open content as a stream for writing.
  
          See DAVResource.begin_write()