Eval math operations

We need to add a tool to eval pure math and bool operations.

For example, we can check that 1 + 2 is 3 and "a" * 2 is "aa" We need it because sometimes we restrict to use several datatypes in some places: like float in dict keys. But, people can actually write float numbers as math expressions: 0.1 + 5 * 10 ^ 2. We have to parse this information and return result nodes.

Algorithm:

• if all elements are constants - return the evaluated result
• if anything fails - return the wrapping node itself

Refs #861

[sobolevn]

Sounds like a good idea. Let’s try it!

[Jrryy]

It is a complicated subject. People usually do not code such operations, but in certain situations it makes the code clearer. For example, if you want a variable to hold an amount of days in seconds, you could write days = x*24*60*60. There are constant operations, but you can clearly see what is stored in this variable.

I suppose I could explore the usage of some of the modules in the project for the purpose of auto improving the code, and use noqas in the cases in which the user would not want the code to be modified.