def calculate_stats(values, **kwargs):
    '''
        Takes a list of numbers (values) and computes some statistics, then
        returns either a specially-formatted string (perhaps suitable for
        writing to a file), a tuple of values, or a dictionary.
        
        store is used to specify the storage (and return) type: 'dict',
        'list', or 'str' (default is list). If 'str' is chosen, then
        the additional options are:
         * delim: the delimiter to use to separate values (default=',')
         * endl: the end-of-line string to use (default='\\n')
         * incl_head: include a header line with the label for each column
           (True or False, default=False)
        
        as_type is used to convert the elements in the values collection
        into the specified type (default is float)
    '''
    
    if not isinstance(values, (list, tuple, set)):
        raise TypeError('values must be a list, tuple, or set')
    
    to_type = kwargs.get('as_type', float)
    values = [to_type(v) for v in values]
    
    retval = []
    labels = []
    
    length = len(values)
    retval.append(length)
    labels.append('length')
    
    total = sum(values)
    retval.append(total)
    labels.append('total')
    
    retval.append(float(total) / length)
    labels.append('mean')
    
    smallest = min(values)
    retval.append(smallest)
    labels.append('min')
    
    largest = max(values)
    retval.append(largest)
    labels.append('max')
    
    retval.append(largest - smallest)
    labels.append('range')
    
    store = kwargs.get('store', list)
    if store in (dict, 'dict'):
        return dict(zip(labels, retval))
    elif store in (str, 'str'):
        delim = kwargs.get('delim', ',')
        end = kwargs.get('endl', '\\n')
        output = ''
        if kwargs.get('incl_head', False):
            output += delim.join(labels) + end
        output += delim.join([str(v) for v in retval]) + end
        return output
    else:
        return labels, retval
    

array = [5.4, 3.5, 7.1, -2.4]
results1 = calculate_stats(array)
print('results1 =', results1)
print()

results2 = calculate_stats(array, store=dict)
print('results2 =', results2)
print()

results3 = calculate_stats(array, store=dict, as_type=int)
print('results3 =', results3)
print()

results4 = calculate_stats(array, store=str, incl_head=True)
print('results4 =', results4)

def squared(x):
    return x*x
results5 = calculate_stats(array, store=dict, as_type=lambda x: x*x)
print('results5 =', results5)
print()