ions like 'tf2ss', which needs the
alignment when dealing with SIMO transfer functions.

Parameters
----------
nums: array_like
    Numerator or list of numerators. Not necessarily with same length.

Returns
-------
nums: array
    The numerator. If `nums` input was a list of numerators then a 2-D
    array with padded zeros for shorter numerators is returned. Otherwise
    returns ``np.asarray(nums)``.
z!dtype of numerator is non-numericc