          super(Lower, self).__init__(expression, **extra)
  
  
  class Substr(Func):
      function = 'SUBSTRING'
  
      def __init__(self, expression, pos, length=None, **extra):
 
</s> remove from django.db.models import IntegerField
 </s> add from django.db.models import DateTimeField, IntegerField </s> remove     Coalesce, Concat, Length, Lower, Substr, Upper,
 </s> add     Coalesce, Concat, Length, Lower, Now, Substr, Upper,
class Now(Func):
    template = 'CURRENT_TIMESTAMP'

    def __init__(self, output_field=None, **extra):
        if output_field is None:
            output_field = DateTimeField()
        super(Now, self).__init__(output_field=output_field, **extra)

    def as_postgresql(self, compiler, connection):
        # Postgres' CURRENT_TIMESTAMP means "the time at the start of the
        # transaction". We use STATEMENT_TIMESTAMP to be cross-compatible with
        # other databases.
        self.template = 'STATEMENT_TIMESTAMP()'
        return self.as_sql(compiler, connection)


          super(Lower, self).__init__(expression, **extra)
  
  
class Now(Func):
    template = 'CURRENT_TIMESTAMP'

    def __init__(self, output_field=None, **extra):
        if output_field is None:
            output_field = DateTimeField()
        super(Now, self).__init__(output_field=output_field, **extra)

    def as_postgresql(self, compiler, connection):
        # Postgres' CURRENT_TIMESTAMP means "the time at the start of the
        # transaction". We use STATEMENT_TIMESTAMP to be cross-compatible with
        # other databases.
        self.template = 'STATEMENT_TIMESTAMP()'
        return self.as_sql(compiler, connection)


  class Substr(Func):
      function = 'SUBSTRING'
  
      def __init__(self, expression, pos, length=None, **extra):
keep keep add keep keep keep keep
 Fixed #24866 -- Added Now() database function 
django/db/models/functions.py