PartOfSpeech constructor Null safety

1. text_analysis
2. text_analysis
3. PartOfSpeech
4. PartOfSpeech const constructor

PartOfSpeech enum

1. Constructors
2. PartOfSpeech
3. Values
4. none
5. symbol
6. emoticon
7. numeral
8. borrowed
9. determiner
10. particle
11. noun
12. pronoun
13. adjective
14. verb
15. adverb
16. preposition
17. conjunction
18. interjection
19. article
20. Properties
21. hashCode
22. index
23. runtimeType
24. Methods
25. noSuchMethod
26. toString
27. Operators
28. operator ==
29. Constants
30. values