Some singles cannot be downloaded in all durations

[chidniu]

First of all, thank you very much for this great tool.

I would like to report the following bug:
There are quite a few single meditation which cannot be downloaded in all durations. For example the "End of Day" Meditation

$ headspace -v pack -d 10 https://my.headspace.com/modes/meditate/content/67

Verbose mode enabled
INFO:pyHeadspace:Getting entity ID
INFO:pyHeadspace:Sending GET request to https://api.prod.headspace.com/content-aggregation/v2/content/view-models/content-info/skeleton
INFO:pyHeadspace:Sending GET request to https://api.prod.headspace.com/content/activity-groups/83
INFO:pyHeadspace:Downloading pack, name: Alone Time
Pack metadata: 
Name:  Alone Time
Description:  Most people lead busy lives. Carving out some alone time—to unwind at the end of a long day, 
to cope during school holidays, or to recover from a hectic week—can create a clearer, calmer mind that 
benefits not only you but those around you.
INFO:pyHeadspace:Sending GET request to https://api.prod.headspace.com/content/activities/1026
Cannot download Alone Time. This could be because this session might not be available in 10 min duration.
This session is available with duration of 5/3/5 minutes. Use --duration option to modify required 
duration.
(Ctrl+C to terminate)
WARNING:pyHeadspace:Cannot download Alone Time. This could be because this session might not be available in 10 min duration.

It seems that the 10 minute option is recognized as 5 minutes which throws the script off.

Some others I have noticed:

• Alone Time
• Frustrated
• For the Weekend