How do I fix this error?

Using Arduino Programming Questions
1 
``` When I try to Upload this code, i get an error message saying "Servo" does not name a type" How do I fix this and how to I understand the code and the error messages that appear?


// constants won't change
const int BUTTON_PIN = 7; // Arduino pin connected to button's pin
const int SERVO_PIN  = 9; // Arduino pin connected to servo motor's pin
const int LED_PIN    = 3; 
Servo servo; // create servo object to control a servo

// variables will change:
int angle = 0;          // the current angle of servo motor
int lastButtonState;    // the previous state of button
int currentButtonState; // the current state of button

void setup() {
  Serial.begin(9600);                // initialize serial
  pinMode(BUTTON_PIN, INPUT_PULLUP); // set arduino pin to input pull-up mode
  servo.attach(SERVO_PIN);           // attaches the servo on pin 9 to the servo object
 // initialize digital pin LED_BUILTIN as an output.
  pinMode(LED_PIN, OUTPUT);
  servo.write(angle);
  currentButtonState = digitalRead(BUTTON_PIN);
}

void loop() {
  lastButtonState    = currentButtonState;      // save the last state
  currentButtonState = digitalRead(BUTTON_PIN); // read new state

  if(lastButtonState == HIGH && currentButtonState == LOW) {
    Serial.println("The button is pressed");

    // change angle of servo motor
    if(angle == 0)
      angle = 180;
    else
    if(angle == 180)
      angle = 0;

    // control servo motor arccoding to the angle
    servo.write(angle);
   digitalWrite(LED_PIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(LED_PIN, LOW);    // turn the LED off by making the voltage LOW
  delay(0);                       // wait for a second
  }
}
2

Maybe insert a

#include "Servo.h"

3

You have not #included the Servo library

#include <Servo.h>
4

thanks so much.

5

it worked

6

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