Should I start a helper function with underscore(s)? [duplicate]

Question

In a module, should I use one, two, or no underscores to denote a helper function the user should not call?

Answer 1

PEP-8, the Python Style Guide, suggests a single leading underscore.

The following special forms using leading or trailing underscores are recognized (these can generally be combined with any case convention):

• _single_leading_underscore: weak "internal use" indicator. E.g. from M import * does not import objects whose name starts with an underscore.
• ...