docs: improve doctests for ndarray instances in stats/base/ndarray/dcumin

[udaykakade25]

Progresses #9329

Description

What is the purpose of this pull request?

This pull request:

• improve doctests for ndarray instances in stats/base/ndarray/dcumin

Related Issues

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This pull request has the following related issues:

• none

Questions

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Other

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Checklist

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• Read, understood, and followed the contributing guidelines.

AI Assistance

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{{TODO: add disclosure if applicable}}

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Coverage Report

Package	Statements	Branches	Functions	Lines
stats/base/ndarray/dcumin	$\color{green}115/115$ $\color{green}+0.00%$	$\color{green}3/3$ $\color{green}+0.00%$	$\color{green}1/1$ $\color{green}+0.00%$	$\color{green}115/115$ $\color{green}+0.00%$

The above coverage report was generated for the changes in this PR.