code: def data(self, ctx=None):
          
          if self._stype != 'default':
              raise RuntimeError("Cannot return a copy of Parameter '%s' on ctx %s via data() " \
                                 "because its storage type is %s. Please use row_sparse_data() " \
                                 "instead." % (self.name, str(ctx), self._stype))
          return self._check_and_get(self._data, ctx)
docs: Returns a copy of this parameter on one context. Must have been
          initialized on this context before. For sparse parameters, use
          :py:meth:`Parameter.row_sparse_data` instead.
  
          Parameters
          ----------
          ctx : Context
              Desired context.
  
          Returns
          -------
          NDArray on ctx