"""
Performs extraction of `what_to_extract` from `*expressions`.
Arguments:
    *expressions (string): Only single value is supported, should be field name to
                           extract from.
    what_to_extract (string): Extraction specificator.
Returns:
    class: Func() expression class, representing 'EXTRACT(`what_to_extract` FROM `*expressions`)'.
"""
Django count grouping by year/month without extra