Travis tests have failed

Hey @cclauss,
Please read the following log in order to understand the failure reason.
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TravisBuddy Request Identifier: 6c665330-afb8-11ea-ae15-c70b0cf57a1c

=========================== short test summary info ============================
FAILED ciphers/affine_cipher.py::affine_cipher.main
FAILED digital_image_processing/resize/resize.py::digital_image_processing.resize.resize.NearestNeighbour.get_y
FAILED divide_and_conquer/convex_hull.py::convex_hull.convex_hull_recursive
FAILED searches/tabu_search.py::tabu_search.find_neighborhood

For L142 in searches/tabu_search.py:

>>> find_neighborhood(['a', 'c', 'b', 'd', 'e', 'a'], {'a': [['b', '20'], ['c', '18'], ['d', '22'], ['e', '26']], 'c': [['a', '18'], ['b', '10'], ['d', '23'], ['e', '24']], 'b': [['a', '20'], ['c', '10'], ['d', '11'], ['e', '12']], 'e': [['a', '26'], ['b', '12'], ['c', '24'], ['d', '40']], 'd': [['a', '22'], ['b', '11'], ['c', '23'], ['e', '40']]})
[['a', 'e', 'b', 'd', 'c', 'a', 90], ['a', 'c', 'd', 'b', 'e', 'a', 90], ['a', 'd', 'b', 'c', 'e', 'a', 93], ['a', 'c', 'b', 'e', 'd', 'a', 102], ['a', 'c', 'e', 'd', 'b', 'a', 113], ['a', 'b', 'c', 'd', 'e', 'a', 119]]

Hey @cclauss,
Something went wrong with the build.

TravisCI finished with status errored, which means the build failed because of something unrelated to the tests, such as a problem with a dependency or the build process itself.

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TravisBuddy Request Identifier: 1d39cec0-afc4-11ea-ae15-c70b0cf57a1c

Hey @cclauss,
Something went wrong with the build.

TravisCI finished with status errored, which means the build failed because of something unrelated to the tests, such as a problem with a dependency or the build process itself.

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TravisBuddy Request Identifier: e271a190-afc4-11ea-ae15-c70b0cf57a1c

Hey @cclauss,
Something went wrong with the build.

TravisCI finished with status errored, which means the build failed because of something unrelated to the tests, such as a problem with a dependency or the build process itself.

View build log

TravisBuddy Request Identifier: 6fad7c00-afc5-11ea-ae15-c70b0cf57a1c

Hey @cclauss,
Something went wrong with the build.

TravisCI finished with status errored, which means the build failed because of something unrelated to the tests, such as a problem with a dependency or the build process itself.

View build log

TravisBuddy Request Identifier: 90aa7610-afc5-11ea-ae15-c70b0cf57a1c

Travis tests have failed

Hey @cclauss,
Please read the following log in order to understand the failure reason.
It'll be awesome if you fix what's wrong and commit the changes.

TravisBuddy Request Identifier: fff149d0-afc6-11ea-ae15-c70b0cf57a1c