DOC: expand gotchas/basics on boolean reductions

Author: jreback

doc/source/basics.rst

@@ -214,6 +214,11 @@ These operations produce a pandas object the same type as the left-hand-side inp
 that if of dtype ``bool``. These ``boolean`` objects can be used in indexing operations,
 see :ref:`here<indexing.boolean>`
 
+Boolean Reductions
+~~~~~~~~~~~~~~~~~~
+
+.. _basics.reductions:
+
 Furthermore, you can apply the reduction functions: ``any()`` and ``all()`` to provide a
 way to summarize these results.
 
@@ -222,6 +227,12 @@ way to summarize these results.
    (df>0).all()
    (df>0).any()
 
+You can reduce to a final boolean value.
+
+.. ipython:: python
+
+   (df>0).any().any()
+
 Finally you can test if a pandas object is empty, via the ``empty`` property.
 
 .. ipython:: python

doc/source/gotchas.rst

@@ -50,6 +50,14 @@ or, you might want to compare if the pandas object is ``None``
            print("I was not None")
     >>> I was not None
 
+.. code-block:: python
+
+    >>> if pd.Series([False, True, False]).any():
+           print("I am any")
+    >>> I am any
+
+See :ref:`boolean reductions<basics.reductions>` for more examples.
+
 Bitwise boolean
 ~~~~~~~~~~~~~~~