diff --git a/data_diff/__main__.py b/data_diff/__main__.py
index 50847b7c..0ad6de11 100644
--- a/data_diff/__main__.py
+++ b/data_diff/__main__.py
@@ -65,8 +65,8 @@ def __init__(self, **kwargs):
         self.indent_increment = 6
 
     def write_usage(self, prog: str, args: str = "", prefix: Optional[str] = None) -> None:
-        self.write(f"data-diff - efficiently diff rows across database tables.\n\n")
-        self.write(f"Usage:\n")
+        self.write("data-diff - efficiently diff rows across database tables.\n\n")
+        self.write("Usage:\n")
         self.write(f"  * In-db diff:    {prog} <database1> <table1> <table2> [OPTIONS]\n")
         self.write(f"  * Cross-db diff: {prog} <database1> <table1> <database2> <table2> [OPTIONS]\n")
         self.write(f"  * Using config:  {prog} --conf PATH [--run NAME] [OPTIONS]\n")
diff --git a/data_diff/databases/base.py b/data_diff/databases/base.py
index 189dced4..b68739d8 100644
--- a/data_diff/databases/base.py
+++ b/data_diff/databases/base.py
@@ -143,7 +143,7 @@ def query(self, sql_ast: Union[Expr, Generator], res_type: type = list):
                     (row,) = row
                 logger.debug("EXPLAIN: %s", row)
             answer = input("Continue? [y/n] ")
-            if not answer.lower() in ["y", "yes"]:
+            if answer.lower() not in ["y", "yes"]:
                 sys.exit(1)
 
         res = self._query(sql_code)
@@ -310,9 +310,9 @@ def offset_limit(self, offset: Optional[int] = None, limit: Optional[int] = None
 
         return f"LIMIT {limit}"
 
-    def concat(self, l: List[str]) -> str:
-        assert len(l) > 1
-        joined_exprs = ", ".join(l)
+    def concat(self, items: List[str]) -> str:
+        assert len(items) > 1
+        joined_exprs = ", ".join(items)
         return f"concat({joined_exprs})"
 
     def is_distinct_from(self, a: str, b: str) -> str:
diff --git a/data_diff/databases/database_types.py b/data_diff/databases/database_types.py
index 86df4489..8adc9fbb 100644
--- a/data_diff/databases/database_types.py
+++ b/data_diff/databases/database_types.py
@@ -151,7 +151,7 @@ def quote(self, s: str):
         ...
 
     @abstractmethod
-    def concat(self, l: List[str]) -> str:
+    def concat(self, items: List[str]) -> str:
         "Provide SQL for concatenating a bunch of columns into a string"
         ...
 
diff --git a/data_diff/databases/oracle.py b/data_diff/databases/oracle.py
index bd849e59..6b4ebe2c 100644
--- a/data_diff/databases/oracle.py
+++ b/data_diff/databases/oracle.py
@@ -127,8 +127,8 @@ def offset_limit(self, offset: Optional[int] = None, limit: Optional[int] = None
 
         return f"FETCH NEXT {limit} ROWS ONLY"
 
-    def concat(self, l: List[str]) -> str:
-        joined_exprs = " || ".join(l)
+    def concat(self, items: List[str]) -> str:
+        joined_exprs = " || ".join(items)
         return f"({joined_exprs})"
 
     def timestamp_value(self, t: DbTime) -> str:
diff --git a/data_diff/databases/redshift.py b/data_diff/databases/redshift.py
index 291d180b..afaa28a4 100644
--- a/data_diff/databases/redshift.py
+++ b/data_diff/databases/redshift.py
@@ -36,8 +36,8 @@ def normalize_timestamp(self, value: str, coltype: TemporalType) -> str:
     def normalize_number(self, value: str, coltype: FractionalType) -> str:
         return self.to_string(f"{value}::decimal(38,{coltype.precision})")
 
-    def concat(self, l: List[str]) -> str:
-        joined_exprs = " || ".join(l)
+    def concat(self, items: List[str]) -> str:
+        joined_exprs = " || ".join(items)
         return f"({joined_exprs})"
 
     def select_table_schema(self, path: DbPath) -> str:
diff --git a/data_diff/databases/vertica.py b/data_diff/databases/vertica.py
index cc606511..6b486555 100644
--- a/data_diff/databases/vertica.py
+++ b/data_diff/databases/vertica.py
@@ -99,8 +99,8 @@ def select_table_schema(self, path: DbPath) -> str:
     def quote(self, s: str):
         return f'"{s}"'
 
-    def concat(self, l: List[str]) -> str:
-        return " || ".join(l)
+    def concat(self, items: List[str]) -> str:
+        return " || ".join(items)
 
     def md5_to_int(self, s: str) -> str:
         return f"CAST(HEX_TO_INTEGER(SUBSTRING(MD5({s}), {1 + MD5_HEXDIGITS - CHECKSUM_HEXDIGITS})) AS NUMERIC(38, 0))"
diff --git a/data_diff/joindiff_tables.py b/data_diff/joindiff_tables.py
index b630d66e..d2dbca61 100644
--- a/data_diff/joindiff_tables.py
+++ b/data_diff/joindiff_tables.py
@@ -2,7 +2,6 @@
 
 """
 
-from contextlib import suppress
 from decimal import Decimal
 from functools import partial
 import logging
@@ -21,7 +20,7 @@
 from .diff_tables import TableDiffer, DiffResult
 from .thread_utils import ThreadedYielder
 
-from .queries import table, sum_, min_, max_, avg, commit
+from .queries import table, sum_, min_, max_, avg
 from .queries.api import and_, if_, or_, outerjoin, leftjoin, rightjoin, this, ITable
 from .queries.ast_classes import Concat, Count, Expr, Random, TablePath
 from .queries.compiler import Compiler
diff --git a/data_diff/utils.py b/data_diff/utils.py
index a2b7e801..de011d02 100644
--- a/data_diff/utils.py
+++ b/data_diff/utils.py
@@ -3,7 +3,7 @@
 import math
 from typing import Iterable, Iterator, MutableMapping, Union, Any, Sequence, Dict
 from typing import TypeVar
-from abc import ABC, abstractmethod
+from abc import abstractmethod
 from urllib.parse import urlparse
 from uuid import UUID
 import operator