The supported subset¶

A script body is Python that Python never runs, so only the part of the language with a faithful Lua meaning is accepted.

Supported: assignment, augmented assignment, if/elif/else, for ... in over a table or range(), while, break, return, comparisons, arithmetic, f-strings, list and dict literals, len(), .append(), int(), float(), str(), min(), max(), abs(), module-level constants, and calls into redis and cjson.

Everything else raises UnsupportedSyntax when the module is imported, with a caret under the line at fault:

'and'/'or' are only supported in an if or while condition
  File "/srv/app/limits.py", line 12
    flag = a and b
           ^
  hint: In Python these return an operand, which does not survive the
  difference in truthiness. Use an if statement instead.

Failing at import, loudly, is deliberate. A body that looks like Python but is never run by Python is exactly where a quiet mistranslation would cost the most.

The gaps that a supported construct still carries — truthiness, 1-based indexing, block scope — are covered in Where Lua differs from Python.