Add xxhash stub (#4689)

third_party/2and3/xxhash.pyi

@@ -0,0 +1,38 @@
+import sys
+from _typeshed import ReadableBuffer
+
+if sys.version_info < (3,):
+    from hashlib import _hash as _Hash
+else:
+    from hashlib import _Hash
+
+VERSION: str
+XXHASH_VERSION: str
+
+class _IntDigestHash(_Hash):
+    def __init__(self, __string: ReadableBuffer = ...): ...
+    def intdigest(self) -> int: ...
+
+# python-xxhash v2.0.0 does not support the string or usedforsecurity kwargs
+class xxh32(_IntDigestHash): ...
+class xxh64(_IntDigestHash): ...
+class xxh3_64(_IntDigestHash): ...
+class xxh3_128(_IntDigestHash): ...
+
+def xxh32_digest(input: ReadableBuffer = ...) -> bytes: ...
+def xxh32_intdigest(input: ReadableBuffer = ...) -> bytes: ...
+def xxh32_hexdigest(input: ReadableBuffer = ...) -> bytes: ...
+def xxh64_digest(input: ReadableBuffer = ...) -> bytes: ...
+def xxh64_intdigest(input: ReadableBuffer = ...) -> bytes: ...
+def xxh64_hexdigest(input: ReadableBuffer = ...) -> bytes: ...
+def xxh3_64_digest(input: ReadableBuffer = ...) -> bytes: ...
+def xxh3_64_intdigest(input: ReadableBuffer = ...) -> bytes: ...
+def xxh3_64_hexdigest(input: ReadableBuffer = ...) -> bytes: ...
+def xxh3_128_digest(input: ReadableBuffer = ...) -> bytes: ...
+def xxh3_128_intdigest(input: ReadableBuffer = ...) -> bytes: ...
+def xxh3_128_hexdigest(input: ReadableBuffer = ...) -> bytes: ...
+
+xxh128 = xxh3_128
+xxh128_digest = xxh3_128_digest
+xxh128_intdigest = xxh3_128_intdigest
+xxh128_hexdigest = xxh3_128_hexdigest