[docs] [issue29968] Document that no characters are allowed to proceed \ in explicit line joining

[Jim Fasarakis-Hilliard]

New submission from Jim Fasarakis-Hilliard:

After looking through the code, the tokenizer only allows a new line character to proceed `\` in explicit line joining [1].

The Devguide section on it [2] actually states many of the limitations of using `\` but not directly that nothing is allowed after it (it does have a remark on comments). 

Would it be a good idea to amend it to state that no characters are allowed after `\`?

[1]: https://github.com/python/cpython/blob/734125938d4653459593ebd28a0aec086efb1f27/Parser/tokenizer.c#L1847
[2]: https://docs.python.org/3/reference/lexical_analysis.html#explicit-line-joining

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assignee: docs at python
components: Documentation
messages: 291067
nosy: Jim Fasarakis-Hilliard, docs at python
priority: normal
severity: normal
status: open
title: Document that no characters are allowed to proceed \ in explicit line joining

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue29968>
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