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with open(input_file, 'r') as in_file, open(output_file, 'w') as out_file: for line in in_file: out_file.write(line) Using the shutil module: import shutil shutil.copyfile(src, dst)

git diff This will show the unstaged changes on the current branch from the commit before it. It will only show changes relative to the index, meaning it shows what you could add to the next commit, but haven't. To add (stage) these changes, you can use git add. If a file is staged, but was modi...

git diff --staged This will show the changes between the previous commit and the currently staged files. NOTE: You can also use the following commands to accomplish the same thing: git diff --cached Which is just a synonym for --staged or git status -v Which will trigger the verbose sett...

str.split(sep=None, maxsplit=-1) str.split takes a string and returns a list of substrings of the original string. The behavior differs depending on whether the sep argument is provided or omitted. If sep isn't provided, or is None, then the splitting takes place wherever there is whitespace. Howe...

Python's str type also has a method for replacing occurences of one sub-string with another sub-string in a given string. For more demanding cases, one can use re.sub. str.replace(old, new[, count]): str.replace takes two arguments old and new containing the old sub-string which is to be replace...

function waitFunc(){ console.log("This will be logged every 5 seconds"); } window.setInterval(waitFunc,5000);

window.setInterval() returns an IntervalID, which can be used to stop that interval from continuing to run. To do this, store the return value of window.setInterval() in a variable and call clearInterval() with that variable as the only argument: function waitFunc(){ console.log("This wil...

git merge incomingBranch This merges the branch incomingBranch into the branch you are currently in. For example, if you are currently in master, then incomingBranch will be merged into master. Merging can create conflicts in some cases. If this happens, you will see the message Automatic merge ...

A generator function is created with a function* declaration. When it is called, its body is not immediately executed. Instead, it returns a generator object, which can be used to "step through" the function's execution. A yield expression inside the function body defines a point at which...

Functions in Swift may return values, throw errors, or both: func reticulateSplines() // no return value and no error func reticulateSplines() -> Int // always returns a value func reticulateSplines() throws // no return value, but may throw an error func reticulat...

A generator is iterable. It can be looped over with a for...of statement, and used in other constructs which depend on the iteration protocol. function* range(n) { for (let i = 0; i < n; ++i) { yield i; } } // looping for (let n of range(10)) { // n takes on the valu...

It is possible to send a value to the generator by passing it to the next() method. function* summer() { let sum = 0, value; while (true) { // receive sent value value = yield; if (value === null) break; // aggregate values sum += value; ...

The removeEventListener() method removes event handlers that have been attached with the addEventListener() method: element.removeEventListener("mousemove", myFunction); Everything (eventname, function, and options) in the removeEventListener must match the one set when adding the even...

You can use slices to very easily reverse a str, list, or tuple (or basically any collection object that implements slicing with the step parameter). Here is an example of reversing a string, although this applies equally to the other types listed above: s = 'reverse me!' s[::-1] # '!em esrever...

When the commits on two branches don't conflict, Git can automatically merge them: ~/Stack Overflow(branch:master) » git merge another_branch Auto-merging file_a Merge made by the 'recursive' strategy. file_a | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

A generator object supports the iterator protocol. That is, it provides a next() method (__next__() in Python 3.x), which is used to step through its execution, and its __iter__ method returns itself. This means that a generator can be used in any language construct which supports generic iterable o...

In addition to receiving values from a generator, it is possible to send an object to a generator using the send() method. def accumulator(): total = 0 value = None while True: # receive sent value value = yield total if value is None: break # aggr...

It's possible to create generator iterators using a comprehension-like syntax. generator = (i * 2 for i in range(3)) next(generator) # 0 next(generator) # 2 next(generator) # 4 next(generator) # raises StopIteration If a function doesn't necessarily need to be passed a list, you can sa...

An external CSS stylesheet can be applied to any number of HTML documents by placing a <link> element in each HTML document. The attribute rel of the <link> tag has to be set to "stylesheet", and the href attribute to the relative or absolute path to the stylesheet. While usin...

A practical use case of a generator is to iterate through values of an infinite series. Here's an example of finding the first ten terms of the Fibonacci Sequence. def fib(a=0, b=1): """Generator that yields Fibonacci numbers. `a` and `b` are the seed values""" ...