create reader for val and var statements declarions

[devcdcc]

In order to reduce the PR size, we are going to split issue #2 into two phases, this is The first one and the next issue #14.

In this issue, we are going to create the basic assignment for non-evaluable values.

example:

val a = 2
var b = 3
c = 4
d: Int = 5
val e: Int = 6

// var declaration
var f: Int = 1
// var update
f = 22