diff --git a/disdrodb/api/checks.py b/disdrodb/api/checks.py
index f5ff494c..b79b38f9 100644
--- a/disdrodb/api/checks.py
+++ b/disdrodb/api/checks.py
@@ -73,8 +73,7 @@ def check_url(url: str) -> bool:
 
     if re.match(regex, url):
         return True
-    else:
-        return False
+    return False
 
 
 def check_path_is_a_directory(dir_path, path_name=""):
diff --git a/disdrodb/api/io.py b/disdrodb/api/io.py
index 0b115a99..4409771c 100644
--- a/disdrodb/api/io.py
+++ b/disdrodb/api/io.py
@@ -270,10 +270,9 @@ def available_campaigns(product, data_sources=None, return_tuple=True, base_dir=
         campaigns = [info[1] for info in list_available_stations]
         campaigns = np.unique(campaigns).tolist()
         return campaigns
-    else:
-        data_source_campaigns = [(info[0], info[1]) for info in list_available_stations]
-        data_source_campaigns = list(set(data_source_campaigns))
-        return data_source_campaigns
+    data_source_campaigns = [(info[0], info[1]) for info in list_available_stations]
+    data_source_campaigns = list(set(data_source_campaigns))
+    return data_source_campaigns
 
 
 def available_stations(
@@ -320,7 +319,7 @@ def available_stations(
 
     if return_tuple:
         return list_info
-    else:
-        # TODO: ENSURE THAT NO DUPLICATED STATION NAMES ?
-        list_stations = [info[2] for info in list_info]
-        return list_stations
+
+    # TODO: ENSURE THAT NO DUPLICATED STATION NAMES ?
+    list_stations = [info[2] for info in list_info]
+    return list_stations
diff --git a/disdrodb/data_transfer/download_data.py b/disdrodb/data_transfer/download_data.py
index 479df5cc..e358524a 100644
--- a/disdrodb/data_transfer/download_data.py
+++ b/disdrodb/data_transfer/download_data.py
@@ -141,7 +141,7 @@ def download_archive(
     metadata_filepaths = _select_metadata_with_remote_data_url(metadata_filepaths)
     if len(metadata_filepaths) == 0:
         print("No available remote data to download.")
-        return None
+        return
 
     # Try to download the data
     # - It will download data only if the disdrodb_data_url is specified !
@@ -211,8 +211,7 @@ def _is_valid_disdrodb_data_url(disdrodb_data_url):
     """Check if it is a valid disdrodb_data_url."""
     if isinstance(disdrodb_data_url, str) and len(disdrodb_data_url) > 10:
         return True
-    else:
-        return False
+    return False
 
 
 def _has_disdrodb_data_url(metadata_filepath):
diff --git a/disdrodb/l0/check_configs.py b/disdrodb/l0/check_configs.py
index 204a63a2..5446b95c 100644
--- a/disdrodb/l0/check_configs.py
+++ b/disdrodb/l0/check_configs.py
@@ -225,6 +225,7 @@ def check_list_length(cls, value):
             if len(value) != 2:
                 raise ValueError(f"data_range must have exactly 2 keys, {len(value)} element have been provided.")
             return value
+        return None
 
 
 def _check_raw_data_format(sensor_name: str) -> None:
diff --git a/disdrodb/l0/l0_processing.py b/disdrodb/l0/l0_processing.py
index 2d879560..731ea418 100644
--- a/disdrodb/l0/l0_processing.py
+++ b/disdrodb/l0/l0_processing.py
@@ -567,7 +567,7 @@ def run_l0b(
 
     # Skip run_l0b processing if the raw data are netCDFs
     if attrs["raw_data_format"] == "netcdf":
-        return None
+        return
 
     # -----------------------------------------------------------------.
     # Start L0B processing
@@ -635,7 +635,7 @@ def run_l0b(
         timedelta_str = str(datetime.timedelta(seconds=time.time() - t_i))
         msg = f"L0B processing of station_name {station_name} completed in {timedelta_str}"
         log_info(logger=logger, msg=msg, verbose=verbose)
-    return None
+    return
 
 
 def run_l0b_from_nc(
diff --git a/disdrodb/l0/l0a_processing.py b/disdrodb/l0/l0a_processing.py
index a5139058..210a605a 100644
--- a/disdrodb/l0/l0a_processing.py
+++ b/disdrodb/l0/l0a_processing.py
@@ -131,7 +131,7 @@ def read_raw_file(
 def _check_df_sanitizer_fun(df_sanitizer_fun):
     """Check that ``df`` is the only argument of ``df_sanitizer_fun``."""
     if df_sanitizer_fun is None:
-        return None
+        return
     if not callable(df_sanitizer_fun):
         raise ValueError("'df_sanitizer_fun' must be a function.")
     if not np.all(np.isin(inspect.getfullargspec(df_sanitizer_fun).args, ["df"])):
@@ -488,7 +488,7 @@ def replace_nan_flags(df, sensor_name, verbose=False):
             if n_nan_flags_values > 0:
                 msg = f"In variable {var}, {n_nan_flags_values} values were nan_flags and were replaced to np.nan."
                 log_info(logger=logger, msg=msg, verbose=verbose)
-                df[var][is_a_nan_flag] = np.nan
+                df.loc[is_a_nan_flag, var] = np.nan
     # Return dataframe
     return df
 
diff --git a/disdrodb/l0/l0b_nc_processing.py b/disdrodb/l0/l0b_nc_processing.py
index dd0abd72..132623ba 100644
--- a/disdrodb/l0/l0b_nc_processing.py
+++ b/disdrodb/l0/l0b_nc_processing.py
@@ -127,7 +127,7 @@ def add_dataset_missing_variables(ds, missing_vars, sensor_name):
         # Get variable dimension
         dims = var_dims_dict[var]
         # Retrieve expected shape
-        expected_shape = [ds.dims[dim] for dim in dims]
+        expected_shape = [ds.sizes[dim] for dim in dims]
         # Create DataArray
         arr = np.zeros(expected_shape) * np.nan
         da = xr.DataArray(arr, dims=dims)
diff --git a/disdrodb/l0/template_tools.py b/disdrodb/l0/template_tools.py
index 71637df8..21fbab95 100644
--- a/disdrodb/l0/template_tools.py
+++ b/disdrodb/l0/template_tools.py
@@ -329,8 +329,7 @@ def str_has_decimal_digits(string: str) -> bool:
     """
     if len(string.split(".")) == 2:
         return True
-    else:
-        return False
+    return False
 
 
 def get_decimal_ndigits(string: str) -> int:
@@ -348,8 +347,7 @@ def get_decimal_ndigits(string: str) -> int:
     """
     if str_has_decimal_digits(string):
         return len(string.split(".")[1])
-    else:
-        return 0
+    return 0
 
 
 def get_natural_ndigits(string: str) -> int:
@@ -369,8 +367,7 @@ def get_natural_ndigits(string: str) -> int:
         return len(string.replace("-", ""))
     if str_has_decimal_digits(string):
         return len(string.split(".")[0].replace("-", ""))
-    else:
-        return 0
+    return 0
 
 
 def get_ndigits(string: str) -> int:
@@ -392,8 +389,7 @@ def get_ndigits(string: str) -> int:
     string = string.replace("-", "")
     if str_has_decimal_digits(string):
         return len(string) - 1  # remove .
-    else:
-        return len(string)
+    return len(string)
 
 
 def get_nchar(string: str) -> int:
diff --git a/disdrodb/metadata/checks.py b/disdrodb/metadata/checks.py
index 0be7b113..0dc05f40 100644
--- a/disdrodb/metadata/checks.py
+++ b/disdrodb/metadata/checks.py
@@ -169,12 +169,10 @@ def _check_lonlat_type(longitude, latitude):
 def _check_lonlat_validity(longitude, latitude):
     if longitude == -9999 or latitude == -9999:
         raise ValueError("Missing lat lon coordinates (-9999).")
-    elif longitude > 180 or longitude < -180:
+    if longitude > 180 or longitude < -180:
         raise ValueError("Invalid longitude (outside [-180, 180])")
-    elif latitude > 90 or latitude < -90:
+    if latitude > 90 or latitude < -90:
         raise ValueError("Invalid latitude (outside [-90, 90])")
-    else:
-        pass
 
 
 def check_metadata_geolocation(metadata) -> None:
@@ -550,8 +548,7 @@ def check_archive_metadata_compliance(base_dir: Optional[str] = None, raise_erro
             msg = msg + f"The error is: {e}."
             if raise_error:
                 raise ValueError(msg)
-            else:
-                print(msg)
+            print(msg)
 
     return is_valid
 
diff --git a/disdrodb/tests/test_l0/test_config_files.py b/disdrodb/tests/test_l0/test_config_files.py
index c0a9be30..200ba62a 100644
--- a/disdrodb/tests/test_l0/test_config_files.py
+++ b/disdrodb/tests/test_l0/test_config_files.py
@@ -90,10 +90,8 @@ def is_sorted_int_keys(obj: list) -> bool:
     if isinstance(obj, list):
         if len(obj) == 0:
             return True
-        else:
-            return all(isinstance(x, int) for x in obj) and obj == sorted(obj)
-    else:
-        return False
+        return all(isinstance(x, int) for x in obj) and obj == sorted(obj)
+    return False
 
 
 def is_numeric_list(obj: list) -> bool:
@@ -112,10 +110,8 @@ def is_numeric_list(obj: list) -> bool:
     if isinstance(obj, list):
         if len(obj) == 0:
             return True
-        else:
-            return all(isinstance(x, (int, float)) for x in obj)
-    else:
-        return False
+        return all(isinstance(x, (int, float)) for x in obj)
+    return False
 
 
 def is_string_list(obj: list) -> bool:
@@ -134,10 +130,8 @@ def is_string_list(obj: list) -> bool:
     if isinstance(obj, list):
         if len(obj) == 0:
             return True
-        else:
-            return all(isinstance(x, str) for x in obj)
-    else:
-        return False
+        return all(isinstance(x, str) for x in obj)
+    return False
 
 
 def validate_schema_pytest(schema_to_validate: Union[str, list], schema: BaseModel) -> bool:
diff --git a/disdrodb/tests/test_l0/test_l0a_processing.py b/disdrodb/tests/test_l0/test_l0a_processing.py
index de144628..ac490d80 100644
--- a/disdrodb/tests/test_l0/test_l0a_processing.py
+++ b/disdrodb/tests/test_l0/test_l0a_processing.py
@@ -597,10 +597,10 @@ def test_read_raw_files():
 
     # Create a test dataframe
     df1 = pd.DataFrame(
-        {"time": pd.date_range(start="2022-01-01", end="2022-01-02", freq="H"), "value": np.random.rand(25)},
+        {"time": pd.date_range(start="2022-01-01", end="2022-01-02", freq="h"), "value": np.random.rand(25)},
     )
     df2 = pd.DataFrame(
-        {"time": pd.date_range(start="2022-01-03", end="2022-01-04", freq="H"), "value": np.random.rand(25)},
+        {"time": pd.date_range(start="2022-01-03", end="2022-01-04", freq="h"), "value": np.random.rand(25)},
     )
     df_list = [df1, df2]
 
@@ -620,8 +620,9 @@ def test_read_raw_files():
     def mock_process_raw_file(filepath, column_names, reader_kwargs, df_sanitizer_fun, sensor_name, verbose):
         if filepath == "test_file1.csv":
             return df1
-        elif filepath == "test_file2.csv":
+        if filepath == "test_file2.csv":
             return df2
+        return None
 
     # Monkey patch the function
     l0a_processing.process_raw_file = mock_process_raw_file
diff --git a/disdrodb/tests/test_l0/test_l0b_processing.py b/disdrodb/tests/test_l0/test_l0b_processing.py
index cd5b20aa..75da8755 100644
--- a/disdrodb/tests/test_l0/test_l0b_processing.py
+++ b/disdrodb/tests/test_l0/test_l0b_processing.py
@@ -97,7 +97,7 @@ def define_test_dummy_configs():
 def test_create_l0b_from_l0a(create_test_config_files):
     # Create a sample DataFrame
     df = pd.DataFrame({
-        "time": pd.date_range("2022-01-01", periods=10, freq="H"),
+        "time": pd.date_range("2022-01-01", periods=10, freq="h"),
         "raw_drop_concentration": np.random.rand(10),
         "raw_drop_average_velocity": np.random.rand(10),
         "raw_drop_number": np.random.rand(10),
diff --git a/disdrodb/utils/compression.py b/disdrodb/utils/compression.py
index ef08ba7f..7f2a1dd5 100644
--- a/disdrodb/utils/compression.py
+++ b/disdrodb/utils/compression.py
@@ -169,8 +169,7 @@ def _compress_file(filepath: str, method: str, skip: bool) -> str:
         if skip:
             print(f"File {filepath} is already compressed. Skipping.")
             return filepath
-        else:
-            raise ValueError(f"File {filepath} is already compressed !")
+        raise ValueError(f"File {filepath} is already compressed !")
 
     extension = COMPRESSION_OPTIONS[method]
     archive_name = os.path.basename(filepath) + extension
diff --git a/disdrodb/utils/directories.py b/disdrodb/utils/directories.py
index 79f03bcb..43fefc1b 100644
--- a/disdrodb/utils/directories.py
+++ b/disdrodb/utils/directories.py
@@ -51,8 +51,7 @@ def list_paths(dir_path, glob_pattern, recursive=False):
     """Return a list of filepaths and directory paths."""
     if not recursive:
         return glob.glob(os.path.join(dir_path, glob_pattern))
-    else:
-        return _recursive_glob(dir_path, glob_pattern)
+    return _recursive_glob(dir_path, glob_pattern)
 
 
 def list_files(dir_path, glob_pattern, recursive=False):
@@ -125,8 +124,7 @@ def is_empty_directory(path):
     paths = os.listdir(path)
     if len(paths) == 0:
         return True
-    else:
-        return False
+    return False
 
 
 def _remove_file_or_directories(path):
@@ -155,7 +153,7 @@ def remove_if_exists(path: str, force: bool = False) -> None:
     """
     # If the path does not exist, do nothing
     if not os.path.exists(path):
-        return None
+        return
 
     # If the path exists and force=False, raise Error
     if not force:
diff --git a/disdrodb/utils/logger.py b/disdrodb/utils/logger.py
index 35d06fcb..4be185e2 100644
--- a/disdrodb/utils/logger.py
+++ b/disdrodb/utils/logger.py
@@ -200,7 +200,7 @@ def define_summary_log(list_logs):
     """
     # LogCaptureHandler of pytest does not have baseFilename attribute, so it returns None
     if list_logs[0] is None:
-        return None
+        return
 
     station_name, logs_dir = _get_logs_dir(list_logs)
 
diff --git a/pyproject.toml b/pyproject.toml
index 50a5a8df..6d64a7ce 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -153,7 +153,7 @@ select = [
     # flake8-bugbear
     # "B",
     # flake8-return
-    # "RET",
+    "RET",
     # flake8-unused-arguments
     # "ARG",
     # flake8-raise
@@ -192,6 +192,7 @@ ignore = [
     "PERF203",
 	"PLW2901",
     "B904",
+	"RET504",
 
     # Docstyle Rules
     "D404", # Docstring can't start with "This"