[Fix] Fix ruff errors and a few type annotations

pyerrors/correlators.py

@@ -7,7 +7,7 @@ import matplotlib.pyplot as plt
 import scipy.linalg
 from .obs import Obs, reweight, correlate, CObs
 from .misc import dump_object, _assert_equal_properties
-from .fits import least_squares
+from .fits import least_squares, Fit_result
 from .roots import find_root
 from . import linalg
 from numpy import float64, int64, ndarray, ufunc

pyerrors/misc.py

@@ -6,11 +6,13 @@ import matplotlib
 import matplotlib.pyplot as plt
 import pandas as pd
 import pickle
-from .obs import Obs
+from .obs import Obs, CObs
 from .version import __version__
 from numpy import float64, int64, ndarray
-from typing import List, Type, Union
+from typing import List, Type, Union, TYPE_CHECKING
 
+if TYPE_CHECKING:
+    from .correlators import Corr
 
 def print_config():
     """Print information about version of python, pyerrors and dependencies."""

pyerrors/mpm.py

@@ -3,7 +3,6 @@ import numpy as np
 import scipy.linalg
 from .obs import Obs
 from .linalg import svd, eig
-from pyerrors.obs import Obs
 from typing import List
 
 

pyerrors/obs.py

@@ -1,4 +1,5 @@
 from __future__ import annotations
+import sys
 import warnings
 import hashlib
 import pickle
@@ -12,7 +13,15 @@ import numdifftools as nd
 from itertools import groupby
 from .covobs import Covobs
 from numpy import bool, float64, int64, ndarray
-from typing import Any, Callable, Dict, List, Optional, Union
+from typing import Any, Callable, Dict, List, Optional, Union, TYPE_CHECKING
+
+if sys.version_info >= (3, 10):
+    from types import NotImplementedType
+else:
+    NotImplementedType = type(NotImplemented)
+
+if TYPE_CHECKING:
+    from .correlators import Corr
 
 # Improve print output of numpy.ndarrays containing Obs objects.
 np.set_printoptions(formatter={'object': lambda x: str(x)})

pyerrors/roots.py

@@ -2,7 +2,7 @@ from __future__ import annotations
 import numpy as np
 import scipy.optimize
 from autograd import jacobian
-from .obs import derived_observable
+from .obs import Obs, derived_observable
 from typing import Callable, List, Union