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However, a generator is an object with persistent state, which can repeatedly enter and leave the same scope. A generator call can then be used in place of a list, or other structure whose elements will be iterated over. Whenever the for loop in the example requires the next item, the generator is called, and yields the next item.
The expression which denotes the collection to loop over is evaluated in list-context, but not flattened by default, and each item of the resulting list is, in turn, aliased to the loop variable(s). List literal example:
lsof is a command meaning "list open files", which is used in many Unix-like systems to report a list of all open files and the processes that opened them. This open source utility was developed and supported by Victor A. Abell, the retired Associate Director of the Purdue University Computing Center.
It ships with most Linux distributions, [230] AmigaOS 4 (using Python 2.7), FreeBSD (as a package), NetBSD, and OpenBSD (as a package) and can be used from the command line (terminal). Many Linux distributions use installers written in Python: Ubuntu uses the Ubiquity installer, while Red Hat Linux and Fedora Linux use the Anaconda installer.
The loop counter is used to decide when the loop should terminate and for the program flow to continue to the next instruction after the loop. A common identifier naming convention is for the loop counter to use the variable names i , j , and k (and so on if needed), where i would be the most outer loop, j the next inner loop, etc.
For example, to list files in the current directory , retain only the lines of ls output containing the string "key" , and view the result in a scrolling page , a user types the following into the command line of a terminal:
The event loop almost always operates asynchronously with the message originator. When the event loop forms the central control flow construct of a program, as it often does, it may be termed the main loop or main event loop. This title is appropriate, because such an event loop is at the highest level of control within the program.
Folds can be regarded as consistently replacing the structural components of a data structure with functions and values. Lists, for example, are built up in many functional languages from two primitives: any list is either an empty list, commonly called nil ([]), or is constructed by prefixing an element in front of another list, creating what is called a cons node ( Cons(X1,Cons(X2,Cons ...