# https://en.wikipedia.org/wiki/Ohm%27s_law from typing import Dict def ohms_law(voltage: float, current: float, resistance: float) -> Dict[str, float]: """ Apply Ohm's Law, on any two given electrical values, which can be voltage, current, and resistance, and then in a Python dict return name/value pair of the zero value. >>> ohms_law(voltage=10, resistance=5, current=0) {'current': 2.0} >>> ohms_law(voltage=0, current=0, resistance=10) Traceback (most recent call last): ... ValueError: One and only one argument must be 0 >>> ohms_law(voltage=0, current=1, resistance=-2) Traceback (most recent call last): ... ValueError: Resistance cannot be negative >>> ohms_law(resistance=0, voltage=-10, current=1) {'resistance': -10.0} >>> ohms_law(voltage=0, current=-1.5, resistance=2) {'voltage': -3.0} """ if (voltage, current, resistance).count(0) != 1: raise ValueError("One and only one argument must be 0") if resistance < 0: raise ValueError("Resistance cannot be negative") if voltage == 0: return {"voltage": float(current * resistance)} elif current == 0: return {"current": voltage / resistance} elif resistance == 0: return {"resistance": voltage / current} else: raise ValueError("Exactly one argument must be 0") if __name__ == "__main__": import doctest doctest.testmod()