Merge pull request #29 from kthyng/tweak

relaxed condition to pass through existing keys

Author: kthyng

cf_pandas/accessor.py

@@ -107,7 +107,11 @@ def __getitem__(self, key: str) -> Union[pd.Series, pd.DataFrame]:
 
         # if key is a coordinate or axes, use a different method to match
         valid_keys = _COORD_NAMES + _AXIS_NAMES
-        if key in valid_keys:
+        # return the key if it is already a name in the object and doesn't need to be interpreted
+        if key in self._obj.keys():
+            col_names = [key]
+
+        elif key in valid_keys:
             col_names = _get_axis_coord(self._obj, key)
 
         else: