This is one of the few files that has intimate knowledge of the pyc file
format. Since it lacks tests it tends to become outdated fairly quickly.
At present it has been broken since the introduction of PEP 552.

Co-authored-by: Guido van Rossum <guido@python.org>
Co-authored-by: Lysandros Nikolaou <lisandrosnik@gmail.com>

When there is a SyntaxError after reading the last input character from
the tokenizer and if no newline follows it, the error message used to be
`unexpected EOF while parsing`, which is wrong.

It now uses os.waitstatus_to_exitcode() to convert os.system() exit
status into an exit code.

Break up COMPARE_OP into four logically distinct opcodes:
* COMPARE_OP for rich comparisons
* IS_OP for 'is' and 'is not' tests
* CONTAINS_OP for 'in' and 'is not' tests
* JUMP_IF_NOT_EXC_MATCH for checking exceptions in 'try-except' statements.

 pathfix.py: Assume all files that end on '.py' are Python scripts when working recursively. 

Add option -a to Tools/Scripts/pathfix.py script: add flags.

This is the converse of GH-15353 -- in addition to plenty of
scripts in the tree that are marked with the executable bit
(and so can be directly executed), there are a few that have
a leading `#!` which could let them be executed, but it doesn't
do anything because they don't have the executable bit set.

Here's a command which finds such files and marks them.  The
first line finds files in the tree with a `#!` line *anywhere*;
the next-to-last step checks that the *first* line is actually of
that form.  In between we filter out files that already have the
bit set, and some files that are meant as fragments to be
consumed by one or another kind of preprocessor.

    $ git grep -l '^#!' \
      | grep -vxFf <( \
          git ls-files --stage \
          | perl -lane 'print $F[3] if (!/^100644/)' \
        ) \
      | grep -ve '\.in$' -e '^Doc/includes/' \
      | while read f; do
          head -c2 "$f" | grep -qxF '#!' \
          && chmod a+x "$f"; \
        done

Add flag -k to pathscript.py script: preserve shebang flags.

Use cffi to access a C API in Python.