further enhancement of DataFrame.insert docstring

Author: pierre-haessig

pandas/core/frame.py

@@ -1844,16 +1844,18 @@ def _set_item(self, key, value):
     def insert(self, loc, column, value, allow_duplicates=False):
         """
         Insert column into DataFrame at specified location.
-        if allow_duplicates is False, Raises Exception if column is already contained in the DataFrame
+        
+        Raises a ValueError if `column` is already contained in the DataFrame,
+        unless `allow_duplicates` is set to True.
 
         Parameters
         ----------
         loc : int
             Insertion index. Must verify 0 <= loc <= len(columns)
         column : string, number, or hashable object
-            label of the column
+            label of the inserted column
         value : int, Series, or array-like
-        allow_duplicates : bool
+        allow_duplicates : bool, optional
         """
         value = self._sanitize_column(column, value)
         self._data.insert(