class_docstr: Calculates the time since the last `True` value.
  
  Description:
      Using a series of Datetimes and a series of Booleans, find the last
      record with a `True` value. Return the seconds elapsed between that record
      and the instance's cutoff time. Return nan if no values are `True`.
  
  Examples:
      >>> from datetime import datetime
      >>> time_since_last_true = TimeSinceLastTrue()
      >>> cutoff_time = datetime(2010, 1, 1, 12, 0, 0)
      >>> times = [datetime(2010, 1, 1, 11, 45, 0),
      ...          datetime(2010, 1, 1, 11, 55, 15),
      ...          datetime(2010, 1, 1, 11, 57, 30)]
      >>> booleans = [True, True, False]
      >>> time_since_last_true(times, booleans, time=cutoff_time)
      285.0
code: def get_function(self):
      def time_since_last_true(datetime_col, bool_col, time=None):
          df = pd.DataFrame(
              {
                  "datetime": datetime_col,
                  "bool": bool_col,
              },
          ).dropna()
          if df.empty:
              return np.nan
          true_indices = df[df["bool"]]
          if true_indices.empty:
              return np.nan
          last_true_index = true_indices.index[-1]
          time_since = time - datetime_col.loc[last_true_index]
          return time_since.total_seconds()
  
      return time_since_last_true
  
imports: import numpy
  import pandas
  from woodwork.column_schema import ColumnSchema
  from woodwork.logical_types import Boolean, BooleanNullable, Datetime, Double
  from featuretools.primitives.base import AggregationPrimitive
label_desc: Use image node_id 1 for calling the TimeSinceLastTrue obj's underlying member method code with example usage: obj.get_function() and returns: time_since_last_true, time_since, np, np