DOC: add concat to docs

Author: tacaswell

cycler.py

@@ -390,6 +390,20 @@ def simplify(self):
         return reduce(add, (_cycler(k, v) for k, v in six.iteritems(trans)))
 
     def concat(self, other):
+        """Concatenate two cyclers.
+
+        The keys must match exactly.
+
+        Parameters
+        ----------
+        other : `Cycler`
+            The `Cycler` instances to concatenate to this one
+
+        Returns
+        -------
+        ret : `Cycler`
+            The concatenated `Cycler`
+        """
         return concat(self, other)
 
 

doc/source/index.rst

@@ -180,6 +180,22 @@ Integer Multiplication
    2 * color_cycle
 
 
+Concatenation
+~~~~~~~~~~~~~
+
+`Cycler` objects can be concatenated either via the :py:meth:`Cycler.concat` method
+
+.. ipython:: python
+
+   color_cycle.concat(color_cycle)
+
+or the top-level :py:func:`concat` function
+
+.. ipython:: python
+
+   from cycler import concat
+   concat(color_cycle, color_cycle)
+
 
 Slicing
 -------