1 files changed, 15 insertions, 5 deletions
diff --git a/sqlglot/helper.py b/sqlglot/helper.py
index ed37e6c..5a0f2ac 100644
--- a/sqlglot/helper.py
+++ b/sqlglot/helper.py
@@ -131,7 +131,7 @@ def subclasses(
     ]
 
 
-def apply_index_offset(expressions: t.List[E], offset: int) -> t.List[E]:
+def apply_index_offset(expressions: t.List[t.Optional[E]], offset: int) -> t.List[t.Optional[E]]:
     """
     Applies an offset to a given integer literal expression.
 
@@ -148,10 +148,10 @@ def apply_index_offset(expressions: t.List[E], offset: int) -> t.List[E]:
 
     expression = expressions[0]
 
-    if expression.is_int:
+    if expression and expression.is_int:
         expression = expression.copy()
         logger.warning("Applying array index offset (%s)", offset)
-        expression.args["this"] = str(int(expression.this) + offset)
+        expression.args["this"] = str(int(expression.this) + offset)  # type: ignore
         return [expression]
 
     return expressions
@@ -225,7 +225,7 @@ def open_file(file_name: str) -> t.TextIO:
 
         return gzip.open(file_name, "rt", newline="")
 
-    return open(file_name, "rt", encoding="utf-8", newline="")
+    return open(file_name, encoding="utf-8", newline="")
 
 
 @contextmanager
@@ -256,7 +256,7 @@ def csv_reader(read_csv: exp.ReadCSV) -> t.Any:
         file.close()
 
 
-def find_new_name(taken: t.Sequence[str], base: str) -> str:
+def find_new_name(taken: t.Collection[str], base: str) -> str:
     """
     Searches for a new name.
 
@@ -356,6 +356,15 @@ def flatten(values: t.Iterable[t.Iterable[t.Any] | t.Any]) -> t.Generator[t.Any,
             yield value
 
 
+def count_params(function: t.Callable) -> int:
+    """
+    Returns the number of formal parameters expected by a function, without counting "self"
+    and "cls", in case of instance and class methods, respectively.
+    """
+    count = function.__code__.co_argcount
+    return count - 1 if inspect.ismethod(function) else count
+
+
 def dict_depth(d: t.Dict) -> int:
     """
     Get the nesting depth of a dictionary.
@@ -374,6 +383,7 @@ def dict_depth(d: t.Dict) -> int:
 
     Args:
         d (dict): dictionary
+
     Returns:
         int: depth
     """