Python для начинающих: All, Any, Zip, Enumerate, Filter, Map

“Yesterday” is the most covered song in history, with over 2,000 versions having been recorded. A spare, haunting song of lost love from the early Beatles catalog, it was sung perfectly by a young Paul McCartney. McCartney dreamed the entire melody before he arranged the music with George Martin. ‘It fell out of bed,’ Paul McCartney once said about the origins of ‘Yesterday.’ ‘I had a piano by my bedside, and I must have dreamed it, because I tumbled out of bed and put my hands on the piano keys and I had a tune in my head. It was just all there, a complete thing. I couldn’t believe it. The working lyrics Paul used to fit the tune before he wrote the actual words started with “Scrambled eggs / Oh my baby how I love your legs / Not as much as I love scrambled eggs.” Picking up on that famous trivia, Jimmy Fallon eventually developed the rest of “Scrambled eggs” and recorded it with Paul.
In simple situations you need not consider them, but they can be extremely useful. Variables may be referenced inside the name of a variable. This is called a computed variable name or a nested variable reference. ’ which in turn expands to ‘z’. ’ here is nested within the outer variable reference. The previous example shows two levels of nesting, but any number of levels is possible. ’, which becomes ‘u’. References to recursively-expanded variables within a variable name are re-expanded in the usual fashion. ’ which becomes ‘Hello’. Nested variable references can also contain modified references and function invocations (see Functions for Transforming Text), just like any other reference. ’, a simple variable reference whose value is ‘Hello’. A computed variable name need not consist entirely of a single variable reference. It can contain several variable references, as well as some invariant text. ‘a.c b.c c.c’ or ‘1.c 2.c 3.c’, depending on the value of a1.
Encoding is needed because of support some internet browsers. What are the cons? Some browsers don’t support including of raw SVG code in CSS, so it must be encoded by e.g. 64 method and the final CSS is then larger. Some of the SVG flags are very large. So including all world flags (over 250 flags) in one CSS doesn’t make any sense because the final size of the CSS will be larger than 4 MB (Fortunately, there are different applications where you don’t need to include all the world flags. E.g. if you want to list different languages on your site. For English language, over 20 flags can be omitted. In some cases, the different rate (relation between width and height) can be a problem. SVG flags are real flags and the rate is different. Some flags have rate 2:1, some 3:2, etc. So flags don’t have the same size.
You can use this function in a conditional to test for the presence of a specific substring in a given string. ‘a’ and ‘’ (the empty string), respectively. See Conditionals that Test Flags, for a practical application of findstring. Returns all whitespace-separated words in text that do match any of the pattern words, removing any words that do not match. The patterns are written using ‘%’, just like the patterns used in the patsubst function above. The filter function can be used to separate out different types of strings (such as file names) in a variable. Returns all whitespace-separated words in text that do not match any of the pattern words, removing the words that do match one or more. This is the exact opposite of the filter function. Sorts the words of list in lexical order, removing duplicate words. The output is a list of words separated by single spaces.
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