Several previous issues state that numbers are considered words, but regular language strings do this differently from camelCase or snakeCase.

When:

1. _.words('my 1st birthday')
2. _.words('my_1st_birthday')
3. _.words('my1stBirthday')

Expected:
All would return either
["my", "1", "st", "birthday"]
or
["my", "1st", "birthday"]

Actual:

1. ["my", "1st", "birthday"]
2. ["my", "1", "st", "birthday"]
3. ["my", "1", "st", "birthday"]

Is it expected that 'nth' is viewed differently in a regular string vs camel or snake case?