before returning). There are many styles of asynchronous interfaces: Callback argument Return a placeholder (Future, Promise, Deferred) Deliver to a queue Callback registry (e.g. POSIX signals) Regardless org/3.5/library/socket.html#socket.socket.connect] (i.e. a (host, port) pair for IPv4; additional fields may be present for IPv6). If a callback is passed, it will be run with the result as an argument 5/library/concurrent.futures.html#module- concurrent.futures] package. class tornado.concurrent.Future Placeholder for an asynchronous result. A Future encapsulates the result of an asynchronous operation. In

returning). There are many styles of asynchronous interfaces: • Callback argument • Return a placeholder (Future, Promise, Deferred) • Deliver to a queue • Callback registry (e.g. POSIX signals) Regardless do not actually make things asynchronous). Asynchronous operations in Tornado generally return placeholder objects (Futures), with the exception of some low-level components like the IOLoop that use callbacks address is a tuple suitable to pass to socket.connect (i.e. a (host, port) pair for IPv4; additional fields may be present for IPv6). If a callback is passed, it will be run with the result as an argument

returning). There are many styles of asynchronous interfaces: • Callback argument • Return a placeholder (Future, Promise, Deferred) • Deliver to a queue • Callback registry (e.g. POSIX signals) Regardless address is a tuple suitable to pass to socket.connect (i.e. a (host, port) pair for IPv4; additional fields may be present for IPv6). If a callback is passed, it will be run with the result as an argument functions for interacting with the concurrent.futures package. class tornado.concurrent.Future Placeholder for an asynchronous result. A Future encapsulates the result of an asynchronous operation. In

returning). There are many styles of asynchronous interfaces: • Callback argument • Return a placeholder (Future, Promise, Deferred) • Deliver to a queue • Callback registry (e.g. POSIX signals) Regardless do not actually make things asynchronous). Asynchronous operations in Tornado generally return placeholder objects (Futures), with the exception of some low-level components like the IOLoop that use callbacks address is a tuple suitable to pass to socket.connect (i.e. a (host, port) pair for IPv4; additional fields may be present for IPv6). If a callback is passed, it will be run with the result as an argument

returning). There are many styles of asynchronous interfaces: • Callback argument • Return a placeholder (Future, Promise, Deferred) • Deliver to a queue • Callback registry (e.g. POSIX signals) Regardless do not actually make things asynchronous). Asynchronous operations in Tornado generally return placeholder objects (Futures), with the exception of some low- level components like the IOLoop that use callbacks address is a tuple suitable to pass to socket.connect (i.e. a (host, port) pair for IPv4; additional fields may be present for IPv6). If a callback is passed, it will be run with the result as an argument

returning). There are many styles of asynchronous interfaces: • Callback argument • Return a placeholder (Future, Promise, Deferred) • Deliver to a queue • Callback registry (e.g. POSIX signals) Regardless do not actually make things asynchronous). Asynchronous operations in Tornado generally return placeholder objects (Futures), with the exception of some low- level components like the IOLoop that use callbacks address is a tuple suitable to pass to socket.connect (i.e. a (host, port) pair for IPv4; additional fields may be present for IPv6). If a callback is passed, it will be run with the result as an argument

returning). There are many styles of asynchronous interfaces: • Callback argument • Return a placeholder (Future, Promise, Deferred) • Deliver to a queue • Callback registry (e.g. POSIX signals) Regardless do not actually make things asynchronous). Asynchronous operations in Tornado generally return placeholder objects (Futures), with the exception of some low- level components like the IOLoop that use callbacks address is a tuple suitable to pass to socket.connect (i.e. a (host, port) pair for IPv4; additional fields may be present for IPv6). If a callback is passed, it will be run with the result as an argument

returning). There are many styles of asynchronous interfaces: • Callback argument • Return a placeholder (Future, Promise, Deferred) • Deliver to a queue • Callback registry (e.g. POSIX signals) Regardless do not actually make things asynchronous). Asynchronous operations in Tornado generally return placeholder objects (Futures), with the exception of some low- level components like the IOLoop that use callbacks address is a tuple suitable to pass to socket.connect (i.e. a (host, port) pair for IPv4; additional fields may be present for IPv6). If a callback is passed, it will be run with the result as an argument

returning). There are many styles of asynchronous interfaces: • Callback argument • Return a placeholder (Future, Promise, Deferred) • Deliver to a queue • Callback registry (e.g. POSIX signals) Regardless do not actually make things asynchronous). Asynchronous operations in Tornado generally return placeholder objects (Futures), with the exception of some low- level components like the IOLoop that use callbacks address is a tuple suitable to pass to socket.connect (i.e. a (host, port) pair for IPv4; additional fields may be present for IPv6). If a callback is passed, it will be run with the result as an argument

before returning). There are many styles of asynchronous interfaces: Callback argument Return a placeholder (Future, Promise, Deferred) Deliver to a queue Callback registry (e.g. POSIX signals) Regardless do not actually make things asynchronous). Asynchronous operations in Tornado generally return placeholder objects (Futures), with the exception of some low-level components like the IOLoop that use callbacks org/3.6/library/socket.html#socket.socket.connect] (i.e. a (host, port) pair for IPv4; additional fields may be present for IPv6). If a callback is passed, it will be run with the result as an argument