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# Electric resistance unit converter
CONVERSION_FACTORS = {
    'ohm':      1,
    'milliohm': 1e-3,
    'microohm': 1e-6,
    'kilohm':   1e3,
    'megaohm':  1e6,
    'gigaohm':  1e9,
}

def convert_resistance(value: float, from_unit: str, to_unit: str) -> float:
    """Convert between resistance units"""
    if from_unit not in CONVERSION_FACTORS:
        raise ValueError(f"Unknown unit: {from_unit}")
    if to_unit not in CONVERSION_FACTORS:
        raise ValueError(f"Unknown unit: {to_unit}")

    # Convert to ohm first, then to target
    in_ohm = value * CONVERSION_FACTORS[from_unit]
    return in_ohm / CONVERSION_FACTORS[to_unit]

def display_all(value: float, unit: str):
    """Show value in all units"""
    for target_unit, factor in CONVERSION_FACTORS.items():
        converted = convert_resistance(value, unit, target_unit)
        print(f"  {converted:.6g} {target_unit}")

# Ohm's law
def ohms_law(voltage=None, current=None, resistance=None):
    """Calculate the missing value using V = I * R"""
    if voltage is None:
        return current * resistance
    if current is None:
        return voltage / resistance
    return voltage / current

# Examples
print("1 kilohm =")
display_all(1, 'kilohm')
print(f"V=5V, R=1kOhm -> I={ohms_law(voltage=5, resistance=1000)*1000:.1f} mA")