Creates tensor product of bases.

def kron_bases(*bases: Dict[str, np.ndarray],
               repeat: int = 1) -> Dict[str, np.ndarray]:
    """Creates tensor product of bases."""
    product_basis = {'': 1}
    for basis in bases * repeat:
        product_basis = {
            name1 + name2: np.kron(matrix1, matrix2)
            for name1, matrix1 in product_basis.items()
            for name2, matrix2 in basis.items()
        }
    return product_basis