Finalize ‘exec’ migration and make it backward compatibility for now

ocrmypdf/__init__.py

@@ -1,4 +1,3 @@
-import os
 import pkg_resources
 
 PROGRAM_NAME = 'ocrmypdf'
@@ -6,5 +5,11 @@ PROGRAM_NAME = 'ocrmypdf'
 VERSION = pkg_resources.get_distribution('ocrmypdf').version
 
 
-def page_number(input_file):
-    return int(os.path.basename(input_file)[0:6])
+# These imports are for v4.x backward compatibility for consumers of ocrmypdf
+# (if any). They are deprecated and will be removed in v5.x.
+from .exec import ghostscript, qpdf, tesseract, unpaper, get_program
+from .exceptions import ExitCode
+from .helpers import page_number, is_iterable_notstr
+
+
+