diff --git a/pandas_ods_reader/parsers/fods.py b/pandas_ods_reader/parsers/fods.py
index b1b0a7e..7607339 100644
--- a/pandas_ods_reader/parsers/fods.py
+++ b/pandas_ods_reader/parsers/fods.py
@@ -1,4 +1,5 @@
 from pathlib import Path
+from typing import Any, Iterator, Union
 
 from lxml import etree
 
@@ -15,11 +16,11 @@ TABLE_CELL_REPEATED_ATTRIB = "number-columns-repeated"
 VALUE_TYPE_ATTRIB = "value-type"
 
 
-def get_doc(file_or_path: Path):
+def get_doc(file_or_path: Path) -> etree._ElementTree:
     return etree.parse(str(file_or_path))
 
 
-def get_sheet(spreadsheet, sheet_id):
+def get_sheet(spreadsheet: etree._Element, sheet_id: Union[str, int]) -> etree._Element:
     namespaces = spreadsheet.nsmap
     if isinstance(sheet_id, str):
         sheet = spreadsheet.find(
@@ -35,7 +36,10 @@ def get_sheet(spreadsheet, sheet_id):
     return tables[sheet_id - 1]
 
 
-def get_rows(doc, sheet_id):
+def get_rows(
+    doc: etree._ElementTree,
+    sheet_id: Union[str, int],
+) -> Iterator[etree._Element]:
     if not isinstance(sheet_id, (str, int)):
         raise ValueError("Sheet id has to be either `str` or `int`")
     root = doc.getroot()
@@ -44,18 +48,16 @@ def get_rows(doc, sheet_id):
         SPREADSHEET_TAG, namespaces=namespaces
     )
     sheet = get_sheet(spreadsheet, sheet_id)
-    rows = sheet.findall(TABLE_ROW_TAG, namespaces=namespaces)
-    for row in rows:
-        yield row
+    return sheet.iterfind(TABLE_ROW_TAG, namespaces=namespaces)
 
 
-def is_float(cell):
+def is_float(cell: etree._Element) -> bool:
     return (
         cell.attrib.get(f"{{{cell.nsmap[OFFICE_KEY]}}}{VALUE_TYPE_ATTRIB}") == "float"
     )
 
 
-def get_value(cell, parsed=False):
+def get_value(cell: etree._Element, parsed: bool = False) -> tuple[Any, int]:
     text = cell.find(TABLE_CELL_TEXT_TAG, namespaces=cell.nsmap)
     if text is None:
         return None, 0