#### Wheatstone Bridge

p
```# https://en.wikipedia.org/wiki/Wheatstone_bridge
from __future__ import annotations

def wheatstone_solver(
resistance_1: float, resistance_2: float, resistance_3: float
) -> float:
"""
This function can calculate the unknown resistance in an wheatstone network,
given that the three other resistances in the network are known.
The formula to calculate the same is:

---------------
|Rx=(R2/R1)*R3|
---------------

Usage examples:
>>> wheatstone_solver(resistance_1=2, resistance_2=4, resistance_3=5)
10.0
>>> wheatstone_solver(resistance_1=356, resistance_2=234, resistance_3=976)
641.5280898876405
>>> wheatstone_solver(resistance_1=2, resistance_2=-1, resistance_3=2)
Traceback (most recent call last):
...
ValueError: All resistance values must be positive
>>> wheatstone_solver(resistance_1=0, resistance_2=0, resistance_3=2)
Traceback (most recent call last):
...
ValueError: All resistance values must be positive
"""

if resistance_1 <= 0 or resistance_2 <= 0 or resistance_3 <= 0:
raise ValueError("All resistance values must be positive")
else:
return float((resistance_2 / resistance_1) * resistance_3)

if __name__ == "__main__":
import doctest

doctest.testmod()
```