gpgme.Context().export() does not allow arbitrary modes

[NewbiZ]

I need to export secret keys from my keyring.

GPGME provides the function `gpgme_op_export()` which allows the user to provide an export mode (see https://www.gnupg.org/documentation/manuals/gpgme/Exporting-Keys.html#Exporting-Keys).
This is particularly useful to export secret keys (e.g. using mode `GPGME_EXPORT_MODE_SECRET`, which is the equivalent of calling `gpg` with `--export-secret-key`).

Currently, `pygpgme` does not expose this flag in the `Context.export()` function.

Snippet from `pygpgme` implementing the export function (from `src/pygpgme-context.c`)

1202 Py_BEGIN_ALLOW_THREADS;
1203 err = gpgme_op_export_ext(self->ctx, (const char **)patterns, 0, keydata);
1204 Py_END_ALLOW_THREADS;

Here we see that the mode flags is hardcoded to 0.