return format price with symbol. Example format(100, 'USD') return '$100'
	pretty(price, currency, abbrev=True, trim=False)
	abbrev:
		True: print value + symbol. Symbol can either be placed before or after value
		False: print value + currency code. currency code is placed behind value
	trim:
		True: trim float value to the maximum digit numbers of that currency
		False: keep number of decimal in initial argument

def pretty(price, currency, *, abbrev=True, trim=True):
	""" return format price with symbol. Example format(100, 'USD') return '$100'
	pretty(price, currency, abbrev=True, trim=False)
	abbrev:
		True: print value + symbol. Symbol can either be placed before or after value
		False: print value + currency code. currency code is placed behind value
	trim:
		True: trim float value to the maximum digit numbers of that currency
		False: keep number of decimal in initial argument """
	currency = validate_currency(currency)
	price = validate_price(price)
	space = '' if nospace(currency) else ' '
	fmtstr = ''
	if trim:
		fmtstr = '{:0,.{x}f}'.format(price, x=decimals(currency)).rstrip('0').rstrip('.')
	else:
		fmtstr = '{:0,}'.format(price).rstrip('0').rstrip('.')
	if abbrev: # use currency symbol
		if issuffix(currency):
			return fmtstr + space + symbol(currency)
		return symbol(currency, native=False) + space + fmtstr
	return fmtstr + ' ' + code(currency)