One more test to add

My code had returned False instead of True in the case below though CheckIO marked the task as solved:

assert hypercube([
           ['w', 'y', 'w', 'w', 'w', 'w'],
           ['y', 'h', 'y', 'w', 'w', 'w'],
           ['w', 'y', 'w', 'w', 'w', 'w'],
           ['w', 'p', 'w', 'e', 'w', 'w'],
           ['w', 'e', 'w', 'b', 'w', 'w'],
           ['w', 'r', 'c', 'u', 'w', 'w']]) == True

The problem was 4 y near h. Will be nice to add it to the tests.