'Create new instance of this class with hilbert_space and args.
This is used to bypass the more complex logic in the ``__new__``
method in cases where you already have the exact ``hilbert_space``
and ``args``. This should be used when you are positive these
arguments are valid, in their final, proper form and want to optimize
the creation of the object.'

@classmethod
def _new_rawargs(cls, hilbert_space, *args, **old_assumptions):

    obj = Expr.__new__(cls, *args, **old_assumptions)
    obj.hilbert_space = hilbert_space
    return obj
