Documentation snippet fixes

docs/device/reactive.md

@@ -49,15 +49,13 @@ The micro:bit’s *scheduler* provides the capability to concurrently execute di
 The first job of the scheduler is to allow multiple *subprograms* to be queued up for later execution . For our purposes, a subprogram is just a statement or sequence of statements in the context of a larger program. Consider the Touch Develop program below for counting button presses.
 
 ```blocks
-export function countButtonPresses() {
-    let count = 0
-    input.onButtonPressed(Button.A, () => {
+input.onButtonPressed(Button.A, () => {
     count = count + 1
-    })
-    basic.forever(() => {
+})
+basic.forever(() => {
     basic.showNumber(count, 150)
-    })
-}
+})
+let count = 0
 ```
 
 The program above contains three statements that execute in order from top to bottom. The first statement

docs/js/call.md

@@ -49,7 +49,7 @@ basic.clearScreen()
 
 It's a syntax error to have a left parenthesis without the "closing" right parenthesis:
 
-```typescript
+```
 basic.clearScreen(
 ```
 

docs/reference/serial.md

@@ -5,7 +5,7 @@ Reading and writing data over a serial connection.
 ```cards
 serial.writeLine("");
 serial.writeNumber(0);
-serial.writeValue(x, 0);
+serial.writeValue("x", 0);
 serial.writeString("");
 serial.readLine();
 serial.redirect(SerialPin.P0, SerialPin.P0, BaudRate.BaudRate115200);