contacts has columns contact_id and phone, entered with spaces,
parentheses, plus signs and hyphens in every combination. Some are missing.
Add a digits column holding only the digits of each number, and a valid
boolean that is True when the result has between 10 and 15 digits inclusive.
A missing phone yields a missing digits and valid False. Return the
original columns plus the two new ones, index unchanged.
Input
contact_id phone
0 1 +1 (415) 555-0100
1 2 020 7946 0958
2 3 12345
3 4 None
Output
contact_id phone digits valid
0 1 +1 (415) 555-0100 14155550100 True
1 2 020 7946 0958 02079460958 True
2 3 12345 12345 False
3 4 None None False