class_docstr: Determines the number of unique days of month.
  
  Description:
      Given a list of datetimes, return the number of unique days
      of month. The maximum value is 31. 2018-01-01 and 2018-02-01
      will be counted as 1 unique day. 2019-01-01 and 2018-01-01
      will also be counted as 1.
  
  Examples:
      >>> from datetime import datetime
      >>> n_unique_days_of_month = NUniqueDaysOfMonth()
      >>> times = [datetime(2019, 1, 1),
      ...          datetime(2019, 2, 1),
      ...          datetime(2018, 2, 1),
      ...          datetime(2019, 1, 2),
      ...          datetime(2019, 1, 3)]
      >>> n_unique_days_of_month(times)
      3
class_docstr_tok: ["Determines","the","number","of","unique","days","of","month",".","Description",":","Given","a","list","of","datetimes",",","return","the","number","of","unique","days","of","month",".","The","maximum","value","is","31",".","2018-01-01","and","2018-02-01","will","be","counted","as","1","unique","day",".","2019-01-01","and","2018-01-01","will","also","be","counted","as","1",".","Examples",":",">",">",">","from","datetime","import","datetime",">",">",">","n_unique_days_of_month","=","NUniqueDaysOfMonth","(",")",">",">",">","times","=","[","datetime","(","2019",",","1",",","1",")",",","...","datetime","(","2019",",","2",",","1",")",",","...","datetime","(","2018",",","2",",","1",")",",","...","datetime","(","2019",",","1",",","2",")",",","...","datetime","(","2019",",","1",",","3",")","]",">",">",">","n_unique_days_of_month","(","times",")","3"]
code: def get_function(self):
      def n_unique_days_of_month(x):
          return x.dropna().dt.day.nunique()
  
      return n_unique_days_of_month
  
imports: from woodwork.column_schema import ColumnSchema
  from woodwork.logical_types import Datetime, Integer
  from featuretools.primitives.base import AggregationPrimitive
label_desc: Use image node_id 1 for calling the NUniqueDaysOfMonth obj's underlying member method code with example usage: obj.get_function() and returns: n_unique_days_of_month, x