def move_down_left(rows, columns, t):
    """ A method that takes coordinates of the bomb, number
    of rows and number of columns of the matrix and
    returns coordinates of neighbour which is located at
    the left-hand side and bellow the bomb. It returns None
    if there isn't such a neighbour """

    x, y = t
    if x == rows or y == 0:
        return None
    else:
        return (x + 1, y - 1)