error[E0412]: cannot find type `Duration` in this scope
  --> src/main.rs:15:27
   |
15 | const HEARTBEAT_INTERVAL: Duration = Duration::from_secs(5);
   |                           ^^^^^^^^ not found in this scope
   |
help: consider importing one of these items
   |
1  | use actix::clock::Duration;
   |
1  | use core::time::Duration;
   |
1  | use crate::clock::Duration;
   |
1  | use std::time::Duration;
   |

error[E0433]: failed to resolve: use of undeclared type `Duration`
  --> src/main.rs:15:38
   |
15 | const HEARTBEAT_INTERVAL: Duration = Duration::from_secs(5);
   |                                      ^^^^^^^^ not found in this scope
   |
help: consider importing one of these items
   |
1  | use actix::clock::Duration;
   |
1  | use core::time::Duration;
   |
1  | use crate::clock::Duration;
   |
1  | use std::time::Duration;
   |

error[E0412]: cannot find type `Duration` in this scope
  --> src/main.rs:16:23
   |
16 | const CLIENT_TIMEOUT: Duration = Duration::from_secs(10);
   |                       ^^^^^^^^ not found in this scope
   |
help: consider importing one of these items
   |
1  | use actix::clock::Duration;
   |
1  | use core::time::Duration;
   |
1  | use crate::clock::Duration;
   |
1  | use std::time::Duration;
   |

error[E0433]: failed to resolve: use of undeclared type `Duration`
  --> src/main.rs:16:34
   |
16 | const CLIENT_TIMEOUT: Duration = Duration::from_secs(10);
   |                                  ^^^^^^^^ not found in this scope
   |
help: consider importing one of these items
   |
1  | use actix::clock::Duration;
   |
1  | use core::time::Duration;
   |
1  | use crate::clock::Duration;
   |
1  | use std::time::Duration;
   |

error[E0412]: cannot find type `Instant` in this scope
  --> src/main.rs:19:9
   |
19 |     hb: Instant,
   |         ^^^^^^^ not found in this scope
   |
help: consider importing one of these items
   |
1  | use actix::clock::Instant;
   |
1  | use crate::clock::Instant;
   |
1  | use std::time::Instant;
   |

error[E0433]: failed to resolve: use of undeclared type `Instant`
  --> src/main.rs:32:20
   |
32 |         Self { hb: Instant::now() }
   |                    ^^^^^^^ not found in this scope
   |
help: consider importing one of these items
   |
1  | use actix::clock::Instant;
   |
1  | use crate::clock::Instant;
   |
1  | use std::time::Instant;
   |

error[E0433]: failed to resolve: use of undeclared type `Duration`
  --> src/main.rs:36:26
   |
36 |         ctx.run_interval(Duration::from_secs(5), |act, ctx| {
   |                          ^^^^^^^^ not found in this scope
   |
help: consider importing one of these items
   |
1  | use actix::clock::Duration;
   |
1  | use core::time::Duration;
   |
1  | use crate::clock::Duration;
   |
1  | use std::time::Duration;
   |

error[E0433]: failed to resolve: use of undeclared type `Instant`
  --> src/main.rs:50:27
   |
50 |                 self.hb = Instant::now();
   |                           ^^^^^^^ not found in this scope
   |
help: consider importing one of these items
   |
1  | use actix::clock::Instant;
   |
1  | use crate::clock::Instant;
   |
1  | use std::time::Instant;
   |

error[E0433]: failed to resolve: use of undeclared type `Instant`
  --> src/main.rs:54:27
   |
54 |                 self.hb = Instant::now();
   |                           ^^^^^^^ not found in this scope
   |
help: consider importing one of these items
   |
1  | use actix::clock::Instant;
   |
1  | use crate::clock::Instant;
   |
1  | use std::time::Instant;
   |