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All right.
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So in this lesson we're going to practice getting an email body from a single text file with a known
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structure.
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I'm going to go ahead and copy this cell right here and then I'm going to paste it down below.
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Our goal is modifying the code in the cell,
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so we just print out the message body instead of the header and the message body.
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Here's what I'm going to do.
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I'm going to delete this line, as well as this line, as well as this line.
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And I'm going to add some code between opening the file and closing the file.
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The first thing I'm going to do is I'm going to create a boolean variable and I'm a call that "is_
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body".
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And then I'm going to set that to False to begin with. Then I'll also create another variable - a list called
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"lines".
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So lines is equal to an empty list.
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So that has the square bracket notation.
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Now what I'm gonna do is I'm going to read all the lines in our file so I'm going to use a loop and I'm going
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to loop through our stream, so I'll say "for line in stream:"  and then inside the loop I'm
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going to check if I'm inside the email body.
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So "if is_body:", "lines.append(line)". What this line of code does is it will
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take our list - lines; and append a single line from our text file to the list if we are inside the email
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body.
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Now the natural question is: How would you know that you're inside the email body?
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Well, if we look at the structure of this email, we know that there is a space between the header and
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the body.
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There is a new line right after the date information in the e-mail header.
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So what we're gonna do is we're going to check for this blank right here. If we hit this blank line,
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this new line, we're going to change our boolean variable to True.
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So "elif line == '\n'" - "\n" is our
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new line character.
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So this checks for somebody having hit Enter on their keyboard essentially.
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Then I'll add a semicolon at the end and then inside this else if statement I'm going to set is_body
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equal to True.
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And that's pretty much our loop. I can close my file after we've read all the individual lines in our
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stream and then all I have to do is maybe print out my email body. So my "email_body" is
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going to be equal to all of my list items maybe joined by a new line.
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So I'll take "'\n'.join(
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lines)". And now let's print out our email_body and hit Shift+Enter and what we see is that our
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loop is working.
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We've cut off our hair and we're left with just the email body. If you found this line of code confusing,
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namely joining all the individual entries in the list with a new line character,
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let's take it out and see how this formatting changes
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if we don't have it.
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So what I'll do is I'll put a hash tag there, comment this out and what I'll also do is comment out this
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line right here
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and instead I'm going to print out my list, which was lines.
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Let's see what this looks like. Here's what we have.
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We've got a new line character,
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then we have the first line in our email - 
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"Dear Mr. Still",
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then another new line character and everything is separated by a comma in this list as the loop
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read it line by line and appended it to our list.
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This is the formatting we would get straight out of our loop, and because this is not very readable, what
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we can do instead is join all the individual entries in the list at the new Line character, and then
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we get something much, much, much more readable.
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Fantastic!
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What we've just done is written the Python code to extract an email body from our raw data. With this
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in hand,
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we can apply this to all the messages in our dataset because they all follow the same pattern.
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And I'm going to show you how to do just that in the next lesson.
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Stay tuned.