gh-142019: Add description about the exponent of result formatted with presentation type 'e'.

[1nftf]

• Issue: Add a description about formatting decimal.Decimal with the e/E symbol by __format__. #142019

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[python-cla-bot]

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[1nftf]

The float.__format__ method internally calls PyOS_double_to_string.

The default PyOS_double_to_string implementation will pad the exponent to 2 digits and use a zero exponent for a zero value.

cpython/Python/pystrtod.c

Line 1204 in 469f191

exp_len = sprintf(p, "%+.02d", exp);

The fallback PyOS_double_to_string implementation will internally call PyOS_snprintf.
This also pad the exponent to 2 digits and use a zero exponent for a zero value.

cpython/Python/pystrtod.c

Line 729 in 469f191

PyOS_snprintf(buffer, buf_size, format, d);

[miss-islington-app]

Thanks @1nftf for the PR, and @hugovk for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14.
🐍🍒⛏🤖

[bedevere-app]

GH-142813 is a backport of this pull request to the 3.14 branch.

[bedevere-app]

GH-142814 is a backport of this pull request to the 3.13 branch.