Challenge 1: Write Then Read — Possible Solution
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with open("output.txt", "w") as file:
    file.write("First line\n")
    file.write("Second line\n")
    file.write("Third line\n")

with open("output.txt", "r") as file:
    for line in file:
        print(line.strip())

Output:
First line
Second line
Third line

WHY THIS WORKS AS AN ANSWER
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The first with open("output.txt", "w") as file: block reuses the
chapter's own "w" mode writing example exactly — three separate
file.write() calls, each ending with an explicit \n newline character,
since write() does not add line breaks automatically the way print()
does. The file closes automatically the moment this with block ends,
per the chapter's context-manager guarantee.

The second with open("output.txt", "r") as file: block opens a BRAND
NEW file handle in read mode, reusing the chapter's own line-by-line
iteration pattern (for line in file:) rather than .read() or
.readlines() — memory-efficient and directly demonstrated in the
chapter's "Opening and Reading Files" section.

.strip() on each line removes the trailing \n that was written into
the file, reusing the exact same .strip() call the chapter's own
reading example used — without it, each printed line would have an
extra blank line after it from the leftover newline character.

Two separate with blocks are used rather than one, because the first
file must be fully written and closed before it can be reliably
reopened and read — writing and reading the same file within a single
open() call would require a different mode entirely (like "r+"), which
this chapter doesn't cover.