code: def resize_dimension(self, dimension, size):
          
          if self.dimensions[dimension] is not None:
              raise ValueError("Dimension '%s' is not unlimited and thus "
                               "cannot be resized." % dimension)
  
          # Resize the dimension.
          self._current_dim_sizes[dimension] = size
  
          for var in self.variables.values():
              new_shape = list(var.shape)
              for i, d in enumerate(var.dimensions):
                  if d == dimension:
                      new_shape[i] = size
              new_shape = tuple(new_shape)
              if new_shape != var.shape:
                  var._h5ds.resize(new_shape)
  
          # Recurse as dimensions are visible to this group and all child groups.
          for i in self.groups.values():
              i.resize_dimension(dimension, size)
docs: Resize a dimension to a certain size.
  
          It will pad with the underlying HDF5 data sets' fill values (usually
          zero) where necessary.