from typing import NewType, reveal_type

T = NewType("T", float)


d = {} | {"one": 1}  # Just a way to create a dict[Unknown, Unknown] and breaking type inference on the "one" key.

reveal_type(d)  # dict[Unknown, Unknown]
reveal_type(d["one"])  # Unknown
reveal_type(1.0 * d["one"])  # Unknown (good)
reveal_type(T(1.0) * d["one"])  # int | float (Err!)


# In most cases, the inference above is harmless.
# However, when working with Numpy arrays, it leads to incorrect types.

import numpy as np

arr = np.array([1, 2, 3, 4, 5])
reveal_type(T(1.0) + arr)  # Unknown
reveal_type(arr * T(1.0))  # Unknown
reveal_type(T(1.0) + arr * T(1.0))  # int | float (incorrect!)

reveal_type(arr.__mul__(T(1.0)))  # Unknown
reveal_type(T(1.0) + arr.__mul__(T(1.0)))  # int | float (incorrect!)