correct a typo in doc of morphism.pyx

[fchapoton]

I have found a typo there. Let us correct this now.

Taking the opportunity to enhance the coverage also.

Component: documentation

Author: Frédéric Chapoton

Branch/Commit: 00f5f0b

Reviewer: Peter Bruin

Issue created by migration from https://trac.sagemath.org/ticket/16696

[fchapoton]

Commit: 3252ceb

[fchapoton]

New commits:

3252ceb

trac 16xxx correct a bad formatting of doc in morphism.pyx + more doc

[fchapoton]

Branch: u/chapoton/16696

[pjbruin]

comment:2

A few minor/trivial comments/questions:

• I don't think the change from Sets to Monoids in the doctest for SetMorphism.__init__() is correct. The numerator function is neither a morphism of additive monoids (numerator(1/2) + numerator(2) != numerator(1/2 + 2)) nor of multiplicative monoids (numerator(1/2) * numerator(2) != numerator(1/2 * 2)).
• What is the reason for changing some docstrings to start with r""" instead of """? If I'm not mistaken, this is only needed if the string contains backslashes. There don't seem to be any backslashes in the ones where you added the r; on the other hand, the docstring of register_as_conversion() does have one (so either it should start with r""" or the backslash in \ZZ should be doubled).
• I am not a native English speaker, but I think "can not" should be "cannot" in this context, and "should not it be" should be "shouldn't it be" or "should it not be". Also, not using the shortened forms in these cases sounds a bit artificial in my opinion. Anyway, this is really starting to descend into trivialities...

[pjbruin]

Reviewer: Peter Bruin

[sagetrac-git]

Changed commit from 3252ceb to 00f5f0b

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

00f5f0b

trac #16696 reviewer's comments

[fchapoton]

comment:4

I have tried to answer your comments.

• put back sets instead of monoids
• put r""" exactly when needed
• wrote "cannot"

Done some more little things

• added one more doc to another function
• turn raise statements into py3 syntax

As my sage seems to be broken right now, I was not able to test.

[vbraun]

Changed branch from u/chapoton/16696 to 00f5f0b