Fixed some type hinting issues.

Signed-off-by: Daniel Scheffler <danschef@gfz-potsdam.de>

gms_preprocessing/model/gms_object.py

@@ -37,7 +37,7 @@ import warnings
 import logging
 from collections import OrderedDict
 from itertools import chain
-from typing import Iterable, List, Union, TYPE_CHECKING  # noqa F401  # flake8 issue
+from typing import Iterable, List, Union, Generator, TYPE_CHECKING  # noqa F401  # flake8 issue
 import psutil
 import time
 from pkg_resources import parse_version
@@ -1647,7 +1647,7 @@ class GMS_object(object):
                            self.MetaObj.to_odict(), overwrite=overwrite)
 
     def to_tiles(self, blocksize=(2048, 2048)):
-        # type: (tuple) -> GMS_object
+        # type: (tuple) -> Generator[GMS_object]
         """Returns a generator object where items represent tiles of the given block size for the GMS object.
 
         # NOTE:  it's better to call get_subset_obj (also takes care of tile map infos)
@@ -1667,7 +1667,7 @@ class GMS_object(object):
             yield tileObj
 
     def to_MGRS_tiles(self, pixbuffer=10, v=False):
-        # type: (int, bool) -> GMS_object
+        # type: (int, bool) -> Generator[GMS_object]
         """Returns a generator object where items represent the MGRS tiles for the GMS object.
 
         :param pixbuffer:   <int> a buffer in pixel values used to generate an overlap between the returned MGRS tiles