Define PythonRowRangeClause using NamedTuple

This is equivalent but this has the benefit of allowing
efining defaults value in Python 3.6, which aren't
available via the `namedtuple` factory
(only have been added in Python 3.7).

See: https://docs.python.org/3/library/typing.html#typing.NamedTuple
See: https://docs.python.org/3/library/collections.html#collections.namedtuple

Signed-off-by: Julien Jerphanion <git@jjerphan.xyz>

python/arcticdb/version_store/processing.py

@@ -12,7 +12,7 @@
 import numpy as np
 import pandas as pd
 
-from typing import Dict
+from typing import Dict, NamedTuple
 
 from arcticdb.exceptions import ArcticNativeException, UserInputException
 from arcticdb.version_store._normalization import normalize_dt_range_to_ts
@@ -266,12 +266,16 @@ def value_list_from_args(*args):
 PythonProjectionClause = namedtuple("PythonProjectionClause", ["name", "expr"])
 PythonGroupByClause = namedtuple("PythonGroupByClause", ["name"])
 PythonAggregationClause = namedtuple("PythonAggregationClause", ["aggregations"])
-PythonRowRangeClause = namedtuple(
- "PythonRowRangeClause", ["row_range_type", "n", "start", "end"], defaults=(None, None, None, None)
-)
 PythonDateRangeClause = namedtuple("PythonDateRangeClause", ["start", "end"])
 
 
+class PythonRowRangeClause(NamedTuple):
+ row_range_type: _RowRangeType
+ n: int = None
+ start: int = None
+ end: int = None
+
+
 class QueryBuilder:
  """
  Build a query to process read results with. Syntax is designed to be similar to Pandas: