def get_index(item, key_table):
    """Description: returns the index of an item of interest in a 2D array.

    Arguments:
        item: item of interest.
        key_table (list): a 2D array to find the item of interest.
    Returns:
        twoD_index (list): a list containing tuples at the first instance for
        every row at which the item of interest is found.
    """
    twoD_index = [(i, row.index(item)) for i, row in enumerate(key_table) if item in row]
    return twoD_index