Officially, variable names in Python can be any length and can consist of uppercase and lowercase letters ( A-Z, a-z ), digits ( 0-9 ), and the underscore character ( ). An additional restriction is...

Officially, variable names in Python can be any length and can consist of uppercase and lowercase letters ( A-Z, a-z ), digits ( 0-9 ), and the underscore character ( ). An additional restriction is that, although a variable name can contain digits, the first character of a variable name cannot be a digit. Python’s most-followed style guide, PEP8 also suggests us to limit each line to 79 characters, so, to be extra careful, we will assume variables can be of at most 7 characters in length.
Now, the question is, how many variable names can there be in Python if we abide by these two rules?