def random_number_name(dist, args):
    """Return a string explaining the dist and args."""
    if dist == 'uniform':
        return dist + ' between ' + str(args[0]) + ' and ' + str(args[1])
    elif dist == 'choice':
        return dist + ' within ' + str(args)
    elif dist == 'truncated_exponential':
        string = 'truncated exponential with mean ' + str(args[0])
        if len(args) > 1:
            string += ', min ' + str(args[1])
        if len(args) > 2:
            string += ', max ' + str(args[2])
        return string
    elif dist == 'constant':
        return dist + ' ' + str(args)
    else:
        raise ValueError('Unknown dist:', str(dist))