There are three types of structures ("structs") that can be created using the
`struct` keyword:

* Tuple structs, which are, basically, named tuples.
* The classic [C structs][1]
* Unit structs, which are field-less structs.

{structs.play}

[1]: http://en.wikipedia.org/wiki/Struct_(C_programming_language)

There are three types of structures ("structs") that can be created using the
`struct` keyword:

* Tuple structs, which are, basically, named tuples.
* The classic [C structs][c_struct]
* Unit structs, which are field-less structs, useful for generics

{structs.play}

[c_struct]: http://en.wikipedia.org/wiki/Struct_(C_programming_language)

Add small explanation for unit structs
Add small explanation for unit structs
