Chapter 12.5 - redundant words "to check"/"to see"

[meni-adin]

• I have searched open and closed issues and pull requests for duplicates, using these search terms:
  chapter 12.5
• I have checked the latest main branch to see if this has already been fixed, in this file:
  book/src/ch12-05-working-with-environment-variables.md

URL to the section(s) of the book with this problem:
https://doc.rust-lang.org/book/ch12-05-working-with-environment-variables.html#implementing-the-search_case_insensitive-function

Description of the problem:
Down the page, just before adding the code to check for the environment variable, this sentence appears:
"Then we’ll use the var function from the env module to check to see if any value has been...".
It seems like either "to check" or "to see" should appear, but not both.

Suggested fix:
Replace the start of the sentence with:
"Then we’ll use the var function from the env module to check if any value has been...".

[chriskrycho]

Concur! Thank you!