Explain the use of the ‘yield’ keyword in Python.

 The 'yield' keyword is used in Python to define a generator function. A generator function is a special type of function that generates a sequence of values, one at a time, instead of returning a single value.

The main difference between a generator function and a regular function is that a generator function uses the 'yield' keyword to return a value, instead of the 'return' keyword. When a generator function is called, it returns a generator object, which can be iterated over using a 'for' loop or other iteration tools.

Here is an example of a simple generator function:

When you run this code, it will output the numbers 1 through 5, one at a time. The generator function 'count_up_to' is called once, and each time it hits a yield statement, it returns the current value of 'count' and pauses its execution until the next iteration. This allows the generator to produce values one at a time, which can be useful for processing large data sets or for producing an infinite sequence.

The 'yield' keyword is a powerful tool for creating efficient, memory-friendly iterators in Python. It is often used in combination with other tools, such as the 'itertools' module, to produce complex, iterative algorithms with a small amount of code.