is a square list of lists

# is_a_square_list_of_lists
# A python procedure which takes one input, and returns the boolean True if:
#   1. the input is a list
#   2. any member lists contains as many members as there are member lists
#   For example, these inputs will return  True:
#   [[1]]
#   [['a', 'b'], ['b', 'c']]
#   [[37, 'b', ['nesting_OK']], ['b', 'c', '']]

def is_a_square_list_of_lists(my_list):
    if isinstance(my_list, list):
        size = len(my_list)
        for row in my_list:
            if len(row) != size:
                return False
        return True
    else:
        return False

def test():
    test_cases = [
                  ([],        True),   
                  ([[]],        False),  # The list contains one list, but the list does not have precisely one member
                  ([[1]],        True), 
                  ([[1, 2], [1, 2]],        True), 
                  ([[1, [2]], [1, 2]],        True), 
                  ([[1, 2, 3], [2, 3, 1], [3, 1, 2]],        True), 
                  ([[1, 2, 3], [2, 3, 1], [3, 1]],        False), 
                  (37,        False), 
                  ('a',        False), 
                 ]
    passes = 0
    for (args, expected_result) in test_cases:
        result = is_a_square_list_of_lists(args)
        if result != expected_result:
            print "Failed when input was: ", args, ".  Expected: ", expected_result, " Got: ", result
        else:
            passes = passes + 1
    print passes, " out of ", len(test_cases), " test cases passed."

test()

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