Adds extra indices for the combinatorial problem.

        Arguments
        ---------
        indices : tuple
        distance_matrix : numpy.ndarray (M,M)

        Example
        -------
        >>> add_indices((1,2), numpy.array((5,5)))
        [(1, 2, 3), (1, 2, 4), (1, 2, 5)]

def add_indices(self, indices, distance_matrix):
        '''Adds extra indices for the combinatorial problem.

        Arguments
        ---------
        indices : tuple
        distance_matrix : numpy.ndarray (M,M)

        Example
        -------
        >>> add_indices((1,2), numpy.array((5,5)))
        [(1, 2, 3), (1, 2, 4), (1, 2, 5)]

        '''
        list_new_indices = []
        for i in range(0, len(distance_matrix)):
            if i not in indices:
                list_new_indices.append(indices + (i,))
        return list_new_indices