// create a quantity with unit.Q(value float64, unit string)
	m1 := unit.Q(33, "N/m2")
	
// conversions to other compatible units can be done with ConvertTo(string)
// which returns a new quantity with the new unit, and 
	if m, ok := unit.Q(6894.757, "N/m2").ConvertTo("lbf.in-2"); ok {
		fmt.Println(m)
	} else {
		fmt.Println("error")
	}
// add your own units with Define(newUnitSymbol string, factorForBaseUnit float64, baseUnit string)
	siFactor, err := unit.Define("foo", 7, "lbf/sq in")
	
// return an SI version of the unit
	m2 = m.ToSI()
	
// split into value and unit
	t := unit.Q(12345, "psi")
	value, symbol := t.Split()
	
// conversion
	t1 := t.In("bar")
	value, ok := t.ConvertTo("bar")
	
// change unit of the quantity to SI
	t.Normalize()
	
// SI prefixes work on SI units (only):
	speed := unit.Q(65, "km/h")
	area := unit.Q(7.1, "um2") // use 'u' for micro
	
// math operations are Add, AddN, Subtract, SubtractN, Mult, MultF, Div, DivF, Neg, Power
	s := unit.Add(unit.Q(3.5, "km"), unit.Q(1.2, "mi")).In("ft").String()
	
// return a quantity with the given unit; calculate new conversion factor.
	quantity, err := unit.ParseSymbol("psi.kg-1")
	
// parse user input
	quantity, err := unit.Parse(" -1,234,566.88 sq in/min  ")
	
// create a Context for maintaining a certain unit and output formatting
	unit.DefineContext(personHeight, "cm", "%.0[1]fcm")
	height := unit.Ctx(personHeight)
	m := height.M(1.75, "m")
	s := height.String(m) // -> "175cm"

// other Contexts e.g.
	unit.DefineContext(landArea, "acre", "%0.[1]f acres")
	unit.DefineContext(money, "$", "%[2]s%.2[1]f") // unit before value
	unit.DefineContext(rainIntensity, "mm/h", "%.1f %s")

//----------
	
// optionally create static types like this:
type Area struct {
	unit.Quantity
	*unit.Context
}

var area, _ = unit.DefineContext("landArea", "acre", "%.1f %s")

func NewArea(m unit.Quantity) (Area, error) {
	if !m.HasCompatibleUnit(area.Symbol()) {
		return Area{}, errors.New(fmt.Sprintf("%v is not a %s", m, area.Name))
	}
	return Area{m, area}, nil
}

func (a Area) String() string {
	return a.Context.String(a.Quantity)
}
...
	a, err := NewArea(unit.Q(2.5, "km2"))
	fmt.Println(a.String()) // => 617.8 acre
//----------

// package main/resource
// create a Quantity based resource with a min and max value.
// you can Deposit and Withdraw from the resource.

	rsc := resource.New(unit.Q(0, "kWh"), unit.Q(500, "kWh"), "")
	rsc.Set(unit.Q(25, "kWh"))
	rsc.Withdraw(unit.Q(1e6, "J"))
	rsc.Deposit(unit.Q(1.23, "kJ"))	
	b := rsc.Balance() // => 24.7226 kWh

//----------

// Kelvin Fahrenheit Celsius conversions 
	var f float64 = unit.CtoF(91.833) //  91.833°C -> 197.2994°F
	var k unit.Quantity = unit.FtoK(-1) // -1°F -> 254.816667K