 So one of the things that we can do inside of computer science is something known as natural language processing and the entire idea of natural language processing is that we're starting to look at sort of the structure of How we as people talk one of the things that we can introduce in this idea is something known as regular expressions Now What are regular expressions? Well, if we look at a word say for example the word Singh Singh has four characters in it si in G one of the things that we can do is we can start to define each one of these as a Way for us to kind of look at this in a pattern First we see that our word has an S and then it kind of follows with an I in and a G One of the things we can do is we can now say let's kind of take this regular Expression and let's look at sort of the pattern that we want to kind of be confirming in our case. I Said that we had S I in G but let's see some of the other kind of tenses of The word saying and some other kind of variations on it. So what do we sing? Well, we sing a song We can sang a song or we sang or we sung a song So one of the commonalities you should be noticing is The second letter in each word was really the only difference in the word So what can we do? well instead of me specifying out each work in Sort of the examples we've used in the past. We could treat this as if it was a string and If I kind of did something like this I could separate each one Into a list X Equals these four words and then I could go in and say if Song in X Song is an X so this would be a true statement versus something like cat So how can we start to maybe be a little bit more? Cleaner with this inside of regular expression for what we can do is we can actually start to separate out What we're looking at so in our case we're looking at the structure of the word In our case we have an S we have a G an in and we have a jury G But this part is sort of a blank space. Is that almost like it can change it can be different kinds And one of the things that we can do with this is we can introduce something like the wild card Now the wild card is dot that we're seeing wild card This allows me to say that now anything can appear Right here. I don't care what but it's going to match sort of the structure that I'm looking for So in our case sing works song works saying works and song works But we do kind of run into a slight issue something like SNG or S3 in G that also Technically speaking works because even though the three is not a letter The wild card does not necessarily care. It's any one of them. So how can we bring this to approach? That is now where we start to introduce the R e library inside of Python