Returns the `name` of the `Category` member with the matching *value*
        or a empty string if no member match.

        Example:

        >>> class Format(Category):
        ...     hour = 'hh'
        ...     minute = 'mm'
        ...     second = 'ss'
        >>> Format.get_name('hh')
        'hour'
        >>> Format.get_name('dd')
        ''

def get_name(cls, value):
        """ Returns the `name` of the `Category` member with the matching *value*
        or a empty string if no member match.

        Example:

        >>> class Format(Category):
        ...     hour = 'hh'
        ...     minute = 'mm'
        ...     second = 'ss'
        >>> Format.get_name('hh')
        'hour'
        >>> Format.get_name('dd')
        ''
        """
        for member in cls:
            if member.value == value:
                return member.name
        return str()