Adds _.bind2

Similar to `_.bind`, but binds a value to the second argument of the function.
I found myself in need of something like this mostly when using _.compose and functions like _.last.

Now I'm able to write things like:
```lua
local last2 = _.bind2(_.last, 2)
_.compose(last2, _.compact)
````

1 files changed, 9 insertions, 0 deletions

diff --git a/doc/tutorial.md b/doc/tutorial.md
index 2645bfa..bbc5b02 100644
--- a/doc/tutorial.md
+++ b/doc/tutorial.md
@@ -1079,6 +1079,15 @@ local sqrt2 = _.bind(math.sqrt,2)
 sqrt2() -- => 1.4142135623731
 ````
 
+### bind2 (f, v)
+
+Binds a value to be the second argument to a function.
+
+```lua
+local last2 = _.bind(_.last,2)
+last2({1,2,3,4,5,6}) -- => {5,6}
+````
+
 ### bindn (f, ...)
 
 Binds a variable number of values to be the first arguments to a function.