def get_arb_comb_xx_label(nr_of_qubits, qubit_idx: int):
    """
    Returns labels of the form "xx0xxx", "xx1xxx", "xx2xxx"
    Length of the label is equal to the number of qubits
    """
    comb_str_0 = list('x'*nr_of_qubits)
    comb_str_0[-(qubit_idx+1)] = '0'
    comb_str_0 = "".join(comb_str_0)

    comb_str_1 = list('x'*nr_of_qubits)
    comb_str_1[-(qubit_idx+1)] = '1'
    comb_str_1 = "".join(comb_str_1)

    comb_str_2 = list('x'*nr_of_qubits)
    comb_str_2[-(qubit_idx+1)] = '2'
    comb_str_2 = "".join(comb_str_2)

    return comb_str_0, comb_str_1, comb_str_2