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Python: Variable naming

greeting is an example of a simple name, but not all names are that simple. Often they include several words: for example, «username». Different languages have different naming styles for variables.

Three main variable naming conventions are sometimes combined. These conventions apply to variable names consisting of several words:

  • kebab-case — the constituent words of the variable are separated by a hyphen (my-super-var)
  • snake_case — underscores (my_super_var) are used to separate the parts
  • CamelCase — each word in the variable is capitalized (MySuperVar)

Variables in Python are generally named in the snake_case style; words are written in lowercase letters and separated by an underscore _. For more details, you can study the section «How to name variables» in the PEP8 standard.

At Hexlet we start with linters nigh on straight away.

Next, let's look at an example of bad practices and consider why they should be avoided.


Create two variables named «first number» and «second number» in English using snake_case. Write 20 into the first variable and -100 into the second variable. Print the product of the numbers written in the resulting variables.

The code will work with any name, and we only check the printed result, so the task is up to you.

The exercise doesn't pass checking. What to do? 😶

If you've reached a deadlock it's time to ask your question in the «Discussions». How ask a question correctly:

  • Be sure to attach the test output, without it it's almost impossible to figure out what went wrong, even if you show your code. It's complicated for developers to execute code in their heads, but having a mistake before their eyes most probably will be helpful.
In my environment the code works, but not here 🤨

Tests are designed so that they test the solution in different ways and against different data. Often the solution works with one kind of input data but doesn't work with others. Check the «Tests» tab to figure this out, you can find hints at the error output.

My code is different from the teacher's one 🤔

It's fine. 🙆 One task in programming can be solved in many different ways. If your code passed all tests, it complies with the task conditions.

In some rare cases, the solution may be adjusted to the tests, but this can be seen immediately.

I've read the lessons but nothing is clear 🙄

It's hard to make educational materials that will suit everyone. We do our best but there is always something to improve. If you see a material that is not clear to you, describe the problem in “Discussions”. It will be great if you'll write unclear points in the question form. Usually, we need a few days for corrections.

By the way, you can participate in courses improvement. There is a link below to the lessons course code which you can edit right in your browser.


  • Coding standard a set of syntactic and stylistic rules for writing code.

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