diff --git a/mlair/data_handler/data_handler_neighbors.py b/mlair/data_handler/data_handler_neighbors.py
index 6c87946eaad5568e1ff59c3988bf8fe469442641..26fe6f8549639019169bf0b894186d354eaddc83 100644
--- a/mlair/data_handler/data_handler_neighbors.py
+++ b/mlair/data_handler/data_handler_neighbors.py
@@ -1,6 +1,10 @@
 __author__ = 'Lukas Leufen'
 __date__ = '2020-07-17'
 
+"""
+WARNING: This data handler is just a prototype and has not been validated to work properly! Use it with caution!
+"""
+
 import datetime as dt
 
 import numpy as np
@@ -19,7 +23,7 @@ number = Union[float, int]
 num_or_list = Union[number, List[number]]
 
 
-class DataHandlerNeighbors(DefaultDataHandler):
+class DataHandlerNeighbors(DefaultDataHandler):  # pragma: no cover
     """Data handler including neighboring stations."""
 
     def __init__(self, id_class, data_path, neighbors=None, min_length=0,
@@ -48,7 +52,7 @@ class DataHandlerNeighbors(DefaultDataHandler):
         return [super(DataHandlerNeighbors, self).get_coordinates()].append(neighbors)
 
 
-def run_data_prep():
+def run_data_prep():  # pragma: no cover
     """Comment: methods just to start write meaningful test routines."""
     data = DummyDataHandler("main_class")
     data.get_X()
@@ -63,7 +67,7 @@ def run_data_prep():
     data_prep.get_data(upsampling=False)
 
 
-def create_data_prep():
+def create_data_prep():  # pragma: no cover
     """Comment: methods just to start write meaningful test routines."""
     path = os.path.join(os.path.dirname(os.path.abspath(__file__)), "testdata")
     station_type = None
@@ -91,7 +95,7 @@ def create_data_prep():
     return data_prep
 
 
-class DummyDataHandler(AbstractDataHandler):
+class DummyDataHandler(AbstractDataHandler):  # pragma: no cover
 
     def __init__(self, name, number_of_samples=None):
         """This data handler takes a name argument and the number of samples to generate. If not provided, a random