* added test case for CYK_parse

* added testcase for CYK_parse

* corrected spacing

* fixed issues like alignment, missing comma etc.

* test case for double tennis problem

* Update planning.py

removed commented print statements.

* test commit

* agents.ipynb

* agents.ipynb

* Fixed all the instances of issue #833

* minor fix and cleared change in agents.ipynb

* Update nlp.py

* add chart parsing test

* add chart parsing section

* add cnf_rules to grammar

* Update nlp.ipynb

* Update test_nlp.py

* add more to CNF section

* Update nlp.py

* add CYK parsing test

* add prob-grammar to notebook

* Update nlp.py

* add weighted choice

* tests for prob grammar + generation

* add test for weighted choice

* Update nlp.py

* Update nlp.py

* Update test_nlp.py

* Add files via upload

* Update nlp.ipynb

* add generate_random

* Update nlp.py

* Update test_nlp.py

* Update nlp.ipynb

* Fix flake8 warnings

* Remove unnecessary #noqa

* Fix doctest

* Modified relevant_pages()

* Additional tests for relevant_pages()

* Add test for determineInlinks()

* Add test for HITS()

* fixed premature updation

* Refactor code to match pseudocode

* Fixed normalize()

* Update test for normalize()

* Exclude test files from flake8 check

* Fix flake8 for main files

* Add flake8 check to build

* Modern string formatting in csp.py.

* Modern string formatting in games.py.

* Modern string formatting in learning.py.

* Modern string formatting in nlp.py.

* Modern string formatting in probability.py.

* Modern string formatting in search.py.

* Replaced {0\!r} by {} if %s.

* Corrected a typo.

* Update search.py

Commenting issues fixed (spacing and punctuation was off sometimes).

* Update agents.py

* Update canvas.py

Grammar

* Update grid.py

* Update learning.py

Added period

* Update logic.py

Fix quoting

* Update mdp.py

Fixed quoting

* Update nlp.py

Capitalization and punctuation fixes

* Update planning.py

* Update probability.py

* Update rl.py

'th' to 'the'

* Update search.py

* Update text.py

* Update utils.py

* Update utils.py

* Update utils.py

* Update learning.py

Typo

* Update utils.py

* Implementing HITS algorithm

* Moving HITS work to nlp.py and test_nlp.py

* modifies Fig. to Figure all over the repository

* fixed a small type in logic.py

* Made Log Usage Consistent in text.py

* Added Explicit Imports from utils

- Fix relative imports in base of is a package or not
- Fix not working notebooks
- Add notebooks to packages sources

Used tool 2to3 to finish the porting to Python 3 plus some fixes by
hand.

These functions, which I had to implement in Python 2.2, are now
available in standard Python.

Fixed error in Chart parses method, where it would
incorrectly return some parses that did not start at the beginning
of the input (and therefore did not span the whole input).