class_docstr: Determines the first datetime from a list of datetimes.
  
  Examples:
      >>> from datetime import datetime
      >>> date_first_event = DateFirstEvent()
      >>> date_first_event([
      ...     datetime(2011, 4, 9, 10, 30, 10),
      ...     datetime(2011, 4, 9, 10, 30, 20),
      ...     datetime(2011, 4, 9, 10, 30, 30)])
      Timestamp('2011-04-09 10:30:10')
code: def get_function(self):
      def date_first_event(x):
          x = x.dropna()
          if x.empty:
              return NaT
          return x.iat[0]
  
      return date_first_event
  
imports: from pandas import NaT
  from woodwork.column_schema import ColumnSchema
  from woodwork.logical_types import Datetime
  from featuretools.primitives.base import AggregationPrimitive
label_desc: Use image node_id 1 for calling the DateFirstEvent obj's underlying member method code with example usage: obj.get_function() and returns: date_first_event, x, NaT