code: def ustack(arrs, axis=0):
      
      v = np.stack(arrs, axis=axis)
      v = _validate_numpy_wrapper_units(v, arrs)
      return v
docs: Join a sequence of arrays along a new axis while preserving units
  
      The axis parameter specifies the index of the new axis in the
      dimensions of the result. For example, if ``axis=0`` it will be the
      first dimension and if ``axis=-1`` it will be the last dimension.
  
      This is a wrapper around np.stack that preserves units. See the
      documentation for np.stack for full details.
  
      Examples
      --------
      >>> from unyt import km
      >>> a = [1, 2, 3]*km
      >>> b = [2, 3, 4]*km
      >>> print(ustack([a, b]))
      [[1 2 3]
       [2 3 4]] km