Make a nice human-readable string out of number.

        Number of decimal places increases as quantity approaches 1.
        CASE: 613421788        RESULT:       585M low_precision:       585M
        CASE: 5307033647       RESULT:      4.94G low_precision:       4.9G
        CASE: 44968414685      RESULT:      41.9G low_precision:      41.9G
        CASE: 838471403472     RESULT:       781G low_precision:       781G
        CASE: 9683209690677    RESULT:      8.81T low_precision:       8.8T
        CASE: 1073741824       RESULT:      1024M low_precision:      1024M
        CASE: 1181116006       RESULT:      1.10G low_precision:       1.1G

        :low_precision: returns less decimal places potentially (default is False)
                        sacrificing precision for more readability.
        :min_symbol: Do not approache if number < min_symbol (default is K)

def auto_unit(self, number,
                  low_precision=False,
                  min_symbol='K'
                  ):
        """Make a nice human-readable string out of number.

        Number of decimal places increases as quantity approaches 1.
        CASE: 613421788        RESULT:       585M low_precision:       585M
        CASE: 5307033647       RESULT:      4.94G low_precision:       4.9G
        CASE: 44968414685      RESULT:      41.9G low_precision:      41.9G
        CASE: 838471403472     RESULT:       781G low_precision:       781G
        CASE: 9683209690677    RESULT:      8.81T low_precision:       8.8T
        CASE: 1073741824       RESULT:      1024M low_precision:      1024M
        CASE: 1181116006       RESULT:      1.10G low_precision:       1.1G

        :low_precision: returns less decimal places potentially (default is False)
                        sacrificing precision for more readability.
        :min_symbol: Do not approache if number < min_symbol (default is K)
        """
        symbols = ('K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y')
        if min_symbol in symbols:
            symbols = symbols[symbols.index(min_symbol):]
        prefix = {
            'Y': 1208925819614629174706176,
            'Z': 1180591620717411303424,
            'E': 1152921504606846976,
            'P': 1125899906842624,
            'T': 1099511627776,
            'G': 1073741824,
            'M': 1048576,
            'K': 1024
        }

        for symbol in reversed(symbols):
            value = float(number) / prefix[symbol]
            if value > 1:
                decimal_precision = 0
                if value < 10:
                    decimal_precision = 2
                elif value < 100:
                    decimal_precision = 1
                if low_precision:
                    if symbol in 'MK':
                        decimal_precision = 0
                    else:
                        decimal_precision = min(1, decimal_precision)
                elif symbol in 'K':
                    decimal_precision = 0
                return '{:.{decimal}f}{symbol}'.format(
                    value, decimal=decimal_precision, symbol=symbol)
        return '{!s}'.format(number)