Writing a program consisting of multiple functions

All problems other than the simplest ones are easier to solve if we first break them down into simpler sub-problems.
- A separate function (or subroutine) can be responsible for each sub-problem.
- A problem that consists of several sub-problems is then handled by a function that calls the subroutines in its body.
It will simplify writing and debugging your program if you include test cases in the file with the program.
It will also help in debugging if you put print statements in the program that show what is happening as it runs. You can later delete (or comment out) these statements.

Practice writing more complicated programs

Consider a simple world of pixel-sized agents, each located at a point in a grid represented by a pair of integers. The whole population is represented as a list of these lists of two numbers. Given an agent in a particular position, we want to know whether it will bump into one of the other agents after moving a certain distance in the x and y directions. Write a program that does this. Here's a file to get you started.
A palindrome is a word, phrase, or sentence which has the same sequence of characters when it is reversed. Punctuation, spaces, and capitalization are ignored. For example, No, sir, away! A papaya war is on! is a palindrome. Write a program that determines whether a sentence is a palindrome. You will need the built-in string functions replace() and lower(). Notice in the documentation how they are used: string.lower() and string.replace(x, y), where string is an expression that evaluates to a string and x and y are strings (x is to be replaced by y) Here's a file to get you started. Notice that you're giving a function that reverses a string. You don't have to understand how this function works; just trust it to do what it's supposed to.