Make validate_opcodes() public, used from Darker

src/darkgraylib/diff.py

@@ -100,7 +100,7 @@ def diff_and_get_opcodes(
     return opcodes
 
 
-def _validate_opcodes(opcodes: List[Tuple[str, int, int, int, int]]) -> None:
+def validate_opcodes(opcodes: List[Tuple[str, int, int, int, int]]) -> None:
     """Make sure every other opcode is an 'equal' tag"""
     if not all(
         (tag1 == "equal") != (tag2 == "equal")
@@ -131,7 +131,7 @@ def opcodes_to_edit_linenums(  # pylint: disable=too-many-locals
     """
     if not opcodes:
         return
-    _validate_opcodes(opcodes)
+    validate_opcodes(opcodes)
 
     # Calculate the last line number beyond which we won't extend with extra context
     # lines
@@ -174,7 +174,7 @@ def opcodes_to_chunks(
     lines for each chunk and concatenating them together.
 
     """
-    _validate_opcodes(opcodes)
+    validate_opcodes(opcodes)
     for _tag, src_start, src_end, dst_start, dst_end in opcodes:
         yield src_start + 1, src.lines[src_start:src_end], dst.lines[dst_start:dst_end]
 
@@ -223,7 +223,7 @@ def map_unmodified_lines(src: TextDocument, dst: TextDocument) -> Dict[int, int]
 
     """
     opcodes = diff_and_get_opcodes(src, dst)
-    _validate_opcodes(opcodes)
+    validate_opcodes(opcodes)
     if not src.string and not dst.string:
         # empty files may get linter messages on line 1
         return {1: 1}