refactoring for followup

saqc/flagger/baseflagger.py

@@ -189,14 +189,14 @@ class BaseFlagger(ABC):
         """
         if isinstance(flag, pd.Series):
             raise TypeError("flag: pd.Series is not allowed")
-        checkflags = set(toSequence(flag, self.GOOD))
+        flags_to_compare = set(toSequence(flag, self.GOOD))
 
         flags = self.getFlags(field, loc)
         cp = COMPARATOR_MAP[comparator]
 
         # notna() to prevent nans to become True, eg.: `np.nan != 0 -> True`
         flagged = flags.notna()
-        for f in checkflags:
+        for f in flags_to_compare:
             if not self.isValidFlag(f):
                 raise ValueError(f"invalid flag: {f}")
             flagged &= cp(flags, f)