update

README.md

@@ -1,2 +1,4 @@
 # docs
 read the [spec](spec)
+
+ - [Variable and function assignment](variable-and-function-assignment)

variable-and-function-assignment/README.md

@@ -9,7 +9,7 @@ To define a variable using the `let` keyword, you need to specify the variable n
 let x = 10
 ```
 
-In this example, we define a variable named `x` and initialise it with a value of `10`. The `let` keyword tells the Argon interpreter to define the variable on the current stack.
+In this example, we define a variable named `x` and initialise it with a value of `10`. The `let` keyword tells the Argon interpreter to define the variable on the current stack. If `x` already exists in the current stack, then it will throw a `Name Error` of `Name Error: variable "x" already exists`.
 
 Method 2: Assigning a value to a variable name
 
@@ -49,6 +49,8 @@ In this example, we define a variable `x` with a value of `10` using `let`. We t
 
 # Function Assignment
 
+`let` works exactly the same way as it does in variable assignment.
+
 ```javascript
 let square(x) = do
   return x * x