[FIX] excess history column for new variables through generic.flag

saqc/funcs/generic.py

@@ -3,7 +3,7 @@
 
 from functools import partial
 from inspect import signature
-from typing import Tuple, Any, Union, Callable
+from typing import Tuple, Union, Callable
 
 import numpy as np
 import pandas as pd
@@ -144,8 +144,8 @@ def process(
 
     >>> lambda temperature, uncertainty: np.round(temperature) * np.sqrt(uncertainty)
     """
-    # we get the data unmaskes in order to also receive flags,
-    # so let's ge to the masking manually
+    # we get the data unmasked in order to also receive flags,
+    # so let's do to the masking manually
     data_masked, _ = _maskData(data, flags, data.columns, to_mask)
     data[field] = _execGeneric(flags, data_masked, func, field, nodata).squeeze()
 
@@ -245,8 +245,8 @@ def flag(
 
     >>> lambda level: np.sqrt(level) > 7
     """
-    # we get the data unmaskes in order to also receive flags,
-    # so let's ge to the masking manually
+    # we get the data unmasked, in order to also receive flags,
+    # so let's do to the masking manually
     data_masked, _ = _maskData(data, flags, data.columns, to_mask)
 
     mask = _execGeneric(flags, data_masked, func, field, nodata).squeeze()
@@ -255,9 +255,6 @@ def flag(
     if not np.issubdtype(mask.dtype, np.bool_):
         raise TypeError(f"generic expression does not return a boolean array")
 
-    if field not in flags.columns:
-        flags[field] = pd.Series(UNFLAGGED, index=mask.index, name=field)
-
-    flags[mask, field] = flag
+    flags[field] = mask.replace({False: UNFLAGGED, True: BAD})
 
     return data, flags