diff --git a/build/py3_8/float_int_stubs.py b/build/py3_8/float_int_stubs.py
new file mode 100644
index 0000000000..fa0bef39c3
--- /dev/null
+++ b/build/py3_8/float_int_stubs.py
@@ -0,0 +1,241 @@
+from __future__ import annotations
+
+import ast
+import os
+from collections.abc import Iterable
+from pathlib import Path
+from typing import Final
+
+from typing_extensions import override
+
+KEEP_FLOAT: Final[frozenset[str]] = frozenset((
+    # Example:
+    # If we didn't want to change the type of the `priority` parameter
+    # of the `register` function in the `Registry` class of markdown/util.pyi
+    # "stubs/Markdown/markdown/util.pyi/Registry.register.priority",
+    # See implementation `_node_path` for details on this identifier string.
+))
+""" identifiers for `float` that we don't want to change to `float | int` """
+
+
+def name_for_target(node: ast.AnnAssign) -> str:
+    return (
+        node.target.id
+        if isinstance(node.target, ast.Name)
+        else node.target.attr
+        if isinstance(node.target, ast.Attribute)
+        else "subscript"
+    )
+
+
+def name_for_node(
+    node: ast.ClassDef
+    | ast.FunctionDef
+    | ast.AsyncFunctionDef
+    | ast.arg
+    | ast.Name
+    | ast.AnnAssign,
+) -> str:
+    return (
+        node.name
+        if isinstance(node, (ast.ClassDef, ast.FunctionDef, ast.AsyncFunctionDef))
+        else node.arg
+        if isinstance(node, ast.arg)
+        else name_for_target(node)
+        if isinstance(node, ast.AnnAssign)
+        else node.id
+    )
+
+
+def has_int_child(node: ast.BinOp) -> bool:
+    if isinstance(node.right, ast.Name) and node.right.id == "int":
+        return True
+    if isinstance(node.left, ast.Name) and node.left.id == "int":
+        return True
+    if isinstance(node.right, ast.BinOp):
+        # assuming "|" is the only BinOp in annotations
+        assert isinstance(node.right.op, ast.BitOr), node.right.op
+        if has_int_child(node.right):
+            return True
+    if isinstance(node.left, ast.BinOp):
+        assert isinstance(node.left.op, ast.BitOr), node.left.op
+        if has_int_child(node.left):
+            return True
+    return False
+
+
+class AnnotationTrackingVisitor(ast.NodeVisitor):
+    parent_stack: list[ast.AST]
+    in_ann: str | None = None
+    floats: list[ast.Name]
+    module: str
+
+    def __init__(self, module: str) -> None:
+        self.parent_stack = []
+        self.floats = []
+        self.module = module
+
+    @override
+    def visit(self, node: ast.AST) -> None:
+        self.parent_stack.append(node)
+        super().visit(node)
+        _ = self.parent_stack.pop()
+
+    @override
+    def visit_AnnAssign(self, node: ast.AnnAssign) -> None:
+        assert len(list(ast.iter_fields(node))) == 4, list(ast.iter_fields(node))
+        # I don't know what the 4th field "simple" is, but it's not an AST.
+
+        self.visit(node.target)
+
+        self.in_ann = name_for_target(node)
+        self.visit(node.annotation)
+        self.in_ann = None
+
+        if node.value:
+            self.visit(node.value)
+
+    @override
+    def visit_arg(self, node: ast.arg) -> None:
+        # arg name str, annotation, type comment str
+        assert len(list(ast.iter_fields(node))) == 3, list(ast.iter_fields(node))
+
+        self.in_ann = node.arg
+        if node.annotation:
+            self.visit(node.annotation)
+        self.in_ann = None
+
+    # NOTE: assuming function return values are actually float if annotated as such.
+    # If we don't want to assume that, rename this to `visit_FunctionDef`:
+    # (probably would also want `visit_AsyncFunctionDef`)
+
+    # @override
+    def _unused(self, node: ast.FunctionDef) -> None:
+        # Copied from implementation of base generic_visit
+        # and modified for "returns"
+        for field, value in ast.iter_fields(node):  # pyright: ignore[reportAny]
+            if isinstance(value, ast.AST):
+                if field == "returns":
+                    self.in_ann = "returns"
+                self.visit(value)
+                if field == "returns":
+                    self.in_ann = None
+            elif isinstance(value, Iterable):
+                for item in value:
+                    if isinstance(item, ast.AST):
+                        self.visit(item)
+
+    def _node_path(self) -> str:
+        """a string that identifies the current node (from `self.parent_stack`)"""
+        strs = [
+            name_for_node(n)
+            for n in self.parent_stack
+            if isinstance(
+                n,
+                (
+                    ast.ClassDef,
+                    ast.FunctionDef,
+                    ast.AsyncFunctionDef,
+                    ast.arg,
+                    ast.Name,
+                    ast.AnnAssign,
+                ),
+            )
+        ]
+        if len(strs) > 0 and strs[-1] == "float":
+            _ = strs.pop()
+        return self.module + "/" + ".".join(strs)
+
+    def _with_int(self) -> bool:
+        """`float | int` already"""
+        assert isinstance(self.parent_stack[-1], ast.Name), self.parent_stack
+        assert self.parent_stack[-1].id == "float", self.parent_stack[-1].id
+        index = len(self.parent_stack) - 2
+        while index >= 0:
+            traverse_node = self.parent_stack[index]
+            if not isinstance(traverse_node, ast.BinOp):
+                return False
+            # assuming "|" is the only BinOp in annotations
+            assert isinstance(traverse_node.op, ast.BitOr), traverse_node.op
+            if has_int_child(traverse_node):
+                return True
+            index -= 1
+        return False
+
+    def _is_final(self) -> bool:
+        assert isinstance(self.parent_stack[-1], ast.Name), self.parent_stack
+        assert self.parent_stack[-1].id == "float", self.parent_stack
+        if len(self.parent_stack) > 1:
+            parent = self.parent_stack[-2]
+            if (
+                isinstance(parent, ast.Subscript)
+                and isinstance(parent.value, ast.Name)
+                and parent.value.id == "Final"
+            ):
+                assert parent.slice is self.parent_stack[-1], parent.slice
+                return True
+        return False
+
+    @override
+    def generic_visit(self, node: ast.AST) -> None:
+        if self.in_ann is not None and isinstance(node, ast.Name) and node.id == "float":
+            assert node is self.parent_stack[-1], self.parent_stack
+
+            if self._with_int() or self._is_final():
+                # There's already some already float | int in typeshed
+                # and assuming `Final[float]` is really float
+                pass
+            else:
+                node_path = self._node_path()
+                if node_path not in KEEP_FLOAT:
+                    self.floats.append(node)
+        super().generic_visit(node)
+
+
+def float_expand(stubs: Path) -> None:
+    """change stubs in the given directory from `float` to `float | int`"""
+    for dir_path, _dir_names, file_names in os.walk(stubs):
+        for file_name in file_names:
+            if not file_name.endswith(".pyi"):
+                continue
+            file_path = Path(dir_path) / file_name
+            rel_path = Path(os.path.relpath(file_path, stubs)).as_posix()
+            file_bytes = Path(file_path).read_bytes()
+            file_parsed = ast.parse(file_bytes)
+            v = AnnotationTrackingVisitor(rel_path)
+            v.visit(file_parsed)
+
+            if len(v.floats) > 0:
+                print(file_path.as_posix())
+                # compute start offset of each line in file
+                lines = file_bytes.split(b"\n")
+                line_starts = [0]
+                for line in lines:
+                    line_starts.append(line_starts[-1] + len(line) + 1)  # +1 for newline
+
+                # process in reverse order to avoid offset changes affecting subsequent replacements
+                v.floats.sort(key=lambda n: (n.lineno, n.col_offset), reverse=True)
+                for fl in v.floats:
+                    assert fl.end_lineno == fl.lineno, fl  # always within 1 line
+                    assert fl.end_col_offset is not None
+                    assert fl.end_col_offset == fl.col_offset + 5  # always "float" 5 chars
+
+                    # calculate offsets in file (from offsets in line)
+                    line_start = line_starts[fl.lineno - 1]
+                    start_offset = line_start + fl.col_offset
+                    end_offset = line_start + fl.end_col_offset
+
+                    assert file_bytes[start_offset:end_offset] == b"float", file_bytes[
+                        start_offset:end_offset
+                    ]
+
+                    file_bytes = (
+                        file_bytes[:start_offset] + b"float | int" + file_bytes[end_offset:]
+                    )
+
+                _ = Path(file_path).write_bytes(file_bytes)
+
+
+if __name__ == "__main__":
+    stubs_with_docs_path = Path("docstubs")
+    float_expand(stubs_with_docs_path)