Defining a function name that starts with a number (in Python 3)?

Question

I have tried creating the following function: def 3utr(): do_something(). However, I get a SyntaxError. Replacing the "3" by "three" fixes the problem.

My questions are:

• Why is it a syntax error?
• Is there a way to have a function name start with a number in Python 3?

Answer 1

It is a syntax error because the language specification does not allow identifiers to start with a digit. So it’s not possible to have function names (which are identifiers) that start with digits in Python.

identifier ::= (letter|"_") (letter | digit | "_")*

Python 2 Language Reference

Within the ASCII range (U+0001..U+007F), the valid characters for identifiers are the same as in Python 2.x: the uppercase and lowercase letters A through Z, the underscore _ and, except for the first character, the digits 0 through 9.

Python 3 Language Reference