Update the readme links, oops

README.md

@@ -50,7 +50,7 @@ following exercises will ask you to make tests pass!
 
 [Testing chapter from the Effective Rust section of the book](https://doc.rust-lang.org/stable/book/testing.html)
 
-- ["tests1.rs"](http://play.rust-lang.org/?code=%2F%2F+This+test+has+a+problem+with+it+--+make+the+test+compile%21+Make+the+test%0A%2F%2F+pass%21+Make+the+test+fail%21+Scroll+down+for+hints+%3A%29%0A%0A%23%5Bcfg%28test%29%5D%0Amod+tests+%7B%0A++++%23%5Btest%5D%0A++++fn+you_can_assert%28%29+%7B%0A++++++++assert%21%28%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+You+don%27t+even+need+to+write+any+code+to+test+--+you+can+just+test+values+and+run+that%2C+even%0A%2F%2F+though+you+wouldn%27t+do+that+in+real+life+%3A%29+%60assert%21%60+is+a+macro+that+needs+an+argument.%0A%2F%2F+Depending+on+the+value+of+the+argument%2C+%60assert%21%60+will+do+nothing+%28in+which+case+the+test+will%0A%2F%2F+pass%29+or+%60assert%21%60+will+panic+%28in+which+case+the+test+will+fail%29.+So+try+giving+different+values%0A%2F%2F+to+%60assert%21%60+and+see+which+ones+compile%2C+which+ones+pass%2C+and+which+ones+fail+%3A%29%0A)
+- ["tests1.rs"](http://play.rust-lang.org/?code=%2F%2F+Tests+are+important+to+ensure+that+your+code+does+what+you+think+it+should+do.%0A%2F%2F+Tests+can+be+run+on+this+file+with+the+following+command%3A%0A%2F%2F+rustc+--test+tests1.rs%0A%0A%2F%2F+This+test+has+a+problem+with+it+--+make+the+test+compile%21+Make+the+test%0A%2F%2F+pass%21+Make+the+test+fail%21+Scroll+down+for+hints+%3A%29%0A%0A%23%5Bcfg%28test%29%5D%0Amod+tests+%7B%0A++++%23%5Btest%5D%0A++++fn+you_can_assert%28%29+%7B%0A++++++++assert%21%28%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+You+don%27t+even+need+to+write+any+code+to+test+--+you+can+just+test+values+and+run+that%2C+even%0A%2F%2F+though+you+wouldn%27t+do+that+in+real+life+%3A%29+%60assert%21%60+is+a+macro+that+needs+an+argument.%0A%2F%2F+Depending+on+the+value+of+the+argument%2C+%60assert%21%60+will+do+nothing+%28in+which+case+the+test+will%0A%2F%2F+pass%29+or+%60assert%21%60+will+panic+%28in+which+case+the+test+will+fail%29.+So+try+giving+different+values%0A%2F%2F+to+%60assert%21%60+and+see+which+ones+compile%2C+which+ones+pass%2C+and+which+ones+fail+%3A%29%0A)
 - ["tests2.rs"](http://play.rust-lang.org/?code=%2F%2F+This+test+has+a+problem+with+it+--+make+the+test+compile%21+Make+the+test%0A%2F%2F+pass%21+Make+the+test+fail%21+Scroll+down+for+hints+%3A%29%0A%0A%23%5Bcfg%28test%29%5D%0Amod+tests+%7B%0A++++%23%5Btest%5D%0A++++fn+you_can_assert_eq%28%29+%7B%0A++++++++assert_eq%21%28%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Like+the+previous+exercise%2C+you+don%27t+need+to+write+any+code+to+get+this+test+to+compile+and%0A%2F%2F+run.+%60assert_eq%21%60+is+a+macro+that+takes+two+arguments+and+compares+them.+Try+giving+it+two%0A%2F%2F+values+that+are+equal%21+Try+giving+it+two+arguments+that+are+different%21+Try+giving+it+two+values%0A%2F%2F+that+are+of+different+types%21+Try+switching+which+argument+comes+first+and+which+comes+second%21%0A)
 - ["tests3.rs"](http://play.rust-lang.org/?code=%2F%2F+This+test+isn%27t+testing+our+function+--+make+it+do+that+in+such+a+way+that%0A%2F%2F+the+test+passes.+Then+write+a+second+test+that+tests+that+we+get+the+result%0A%2F%2F+we+expect+to+get+when+we+call+%60is_even%285%29%60.+Scroll+down+for+hints%21%0A%0Apub+fn+is_even%28num%3A+i32%29+-%3E+bool+%7B%0A++++num+%25+2+%3D%3D+0%0A%7D%0A%0A%23%5Bcfg%28test%29%5D%0Amod+tests+%7B%0A++++use+super%3A%3A*%3B%0A%0A++++%23%5Btest%5D%0A++++fn+is_true_when_even%28%29+%7B%0A++++++++assert%21%28false%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+You+can+call+a+function+right+where+you%27re+passing+arguments+to+%60assert%21%60+--+so+you+could+do%0A%2F%2F+something+like+%60assert%21%28having_fun%28%29%29%60.+If+you+want+to+check+that+you+indeed+get+false%2C+you%0A%2F%2F+can+negate+the+result+of+what+you%27re+doing+using+%60%21%60%2C+like+%60assert%21%28%21having_fun%28%29%29%60.%0A)
 - ["tests4.rs"](http://play.rust-lang.org/?code=%2F%2F+This+test+isn%27t+testing+our+function+--+make+it+do+that+in+such+a+way+that%0A%2F%2F+the+test+passes.+Then+write+a+second+test+that+tests+that+we+get+the+result%0A%2F%2F+we+expect+to+get+when+we+call+%60times_two%60+with+a+negative+number.%0A%2F%2F+No+hints%2C+you+can+do+this+%3A%29%0A%0Apub+fn+times_two%28num%3A+i32%29+-%3E+i32+%7B%0A++++num+*+2%0A%7D%0A%0A%23%5Bcfg%28test%29%5D%0Amod+tests+%7B%0A++++use+super%3A%3A*%3B%0A%0A++++%23%5Btest%5D%0A++++fn+returns_twice_of_positive_numbers%28%29+%7B%0A++++++++assert_eq%21%284%2C+4%29%3B%0A++++%7D%0A%7D%0A)
@@ -59,15 +59,15 @@ following exercises will ask you to make tests pass!
 
 [Relevant chapter in The Rust Programming Language](https://doc.rust-lang.org/stable/book/if.html)
 
-- ["if1.rs"](http://play.rust-lang.org/?code=fn+bigger%28a%3A+i32%2C+b%3Ai32%29+-%3E+i32+%7B%0A++++%2F%2F+Complete+this+function+to+return+the+bigger+number%21%0A++++%2F%2F+Do+not+use%3A%0A++++%2F%2F+-+return%0A++++%2F%2F+-+another+function+call%0A++++%2F%2F+-+additional+variables%0A++++%2F%2F+Scroll+down+for+hints.%0A%7D%0A%0Afn+main%28%29+%7B%0A++++assert_eq%21%2810%2C+bigger%2810%2C+8%29%29%3B%0A++++assert_eq%21%2842%2C+bigger%2832%2C+42%29%29%3B%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+It%27s+possible+to+do+this+in+one+line+if+you+would+like%21%0A%2F%2F+Some+similar+examples+from+other+languages%3A%0A%2F%2F+-+In+C%28%2B%2B%29+this+would+be%3A+%60a+%3E+b+%3F+a+%3A+b%60%0A%2F%2F+-+In+Python+this+would+be%3A++%60a+if+a+%3E+b+else+b%60%0A%2F%2F+Remember+in+Rust+that%3A%0A%2F%2F+-+the+%60if%60+condition+does+not+need+to+be+surrounded+by+parentheses%0A%2F%2F+-+%60if%60%2F%60else%60+conditionals+are+expressions%0A%2F%2F+-+Each+condition+is+followed+by+a+%60%7B%7D%60+block.%0A)
+- ["if1.rs"](http://play.rust-lang.org/?code=pub+fn+bigger%28a%3A+i32%2C+b%3Ai32%29+-%3E+i32+%7B%0A++++%2F%2F+Complete+this+function+to+return+the+bigger+number%21%0A++++%2F%2F+Do+not+use%3A%0A++++%2F%2F+-+return%0A++++%2F%2F+-+another+function+call%0A++++%2F%2F+-+additional+variables%0A++++%2F%2F+Scroll+down+for+hints.%0A%7D%0A%0A%23%5Bcfg%28test%29%5D%0Amod+tests+%7B%0A++++use+super%3A%3A*%3B%0A%0A++++%23%5Btest%5D%0A++++fn+ten_is_bigger_than_eight%28%29+%7B%0A++++++++assert_eq%21%2810%2C+bigger%2810%2C+8%29%29%3B%0A++++%7D%0A%0A++++%23%5Btest%5D%0A++++fn+fortytwo_is_bigger_than_thirtytwo%28%29+%7B%0A++++++++assert_eq%21%2842%2C+bigger%2832%2C+42%29%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+It%27s+possible+to+do+this+in+one+line+if+you+would+like%21%0A%2F%2F+Some+similar+examples+from+other+languages%3A%0A%2F%2F+-+In+C%28%2B%2B%29+this+would+be%3A+%60a+%3E+b+%3F+a+%3A+b%60%0A%2F%2F+-+In+Python+this+would+be%3A++%60a+if+a+%3E+b+else+b%60%0A%2F%2F+Remember+in+Rust+that%3A%0A%2F%2F+-+the+%60if%60+condition+does+not+need+to+be+surrounded+by+parentheses%0A%2F%2F+-+%60if%60%2F%60else%60+conditionals+are+expressions%0A%2F%2F+-+Each+condition+is+followed+by+a+%60%7B%7D%60+block.%0A)
 
 ### Strings
 
 [Relevant chapter in The Rust Programming Language](https://doc.rust-lang.org/stable/book/strings.html)
 
 - ["strings1.rs"](http://play.rust-lang.org/?code=%2F%2F+Make+me+compile+without+changing+the+function+signature%21+Scroll+down+for+hints+%3A%29%0A%0Afn+main%28%29+%7B%0A++++let+answer+%3D+current_favorite_color%28%29%3B%0A++++println%21%28%22My+current+favorite+color+is+%7B%7D%22%2C+answer%29%3B%0A%7D%0A%0Afn+current_favorite_color%28%29+-%3E+String+%7B%0A++++%22blue%22%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+The+%60current_favorite_color%60+function+is+currently+returning+a+string+slice+with+the+%60%27static%60%0A%2F%2F+lifetime.+We+know+this+because+the+data+of+the+string+lives+in+our+code+itself+--+it+doesn%27t%0A%2F%2F+come+from+a+file+or+user+input+or+another+program+--+so+it+will+live+as+long+as+our+program%0A%2F%2F+lives.+But+it+is+still+a+string+slice.+There%27s+one+way+to+create+a+%60String%60+by+converting+a%0A%2F%2F+string+slice+covered+in+the+Strings+chapter+of+the+book%2C+and+another+way+that+uses+the+%60From%60%0A%2F%2F+trait.%0A)
-- ["strings2.rs"](http://play.rust-lang.org/?code=%2F%2F+Make+me+compile+without+changing+the+function+signature%21+Scroll+down+for+hints+%3A%29%0A%0Afn+main%28%29+%7B%0A++++let+word+%3D+String%3A%3Afrom%28%22green%22%29%3B+%2F%2F+Try+not+changing+this+line+%3A%29%0A++++if+is_a_color_word%28word%29+%7B%0A++++++++println%21%28%22That+is+a+color+word+I+know%21%22%29%3B%0A++++%7D+else+%7B%0A++++++++println%21%28%22That+is+not+a+color+word+I+know.%22%29%3B%0A++++%7D%0A%7D%0A%0Afn+is_a_color_word%28attempt%3A+%26str%29+-%3E+bool+%7B%0A++++attempt+%3D%3D+%22green%22+%7C%7C+attempt+%3D%3D+%22blue%22+%7C%7C+attempt+%3D%3D+%22red%22%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Yes%2C+it+would+be+really+easy+to+fix+this+by+just+changing+the+value+bound+to+%60guess1%60+to+be+a%0A%2F%2F+string+slice+instead+of+a+%60String%60%2C+wouldn%27t+it%3F%3F+There+is+a+way+to+add+one+character+to+line%0A%2F%2F+5%2C+though%2C+that+will+coerce+the+%60String%60+into+a+string+slice.%0A)
+- ["strings2.rs"](http://play.rust-lang.org/?code=%2F%2F+Make+me+compile+without+changing+the+function+signature%21+Scroll+down+for+hints+%3A%29%0A%0Afn+main%28%29+%7B%0A++++let+word+%3D+String%3A%3Afrom%28%22green%22%29%3B+%2F%2F+Try+not+changing+this+line+%3A%29%0A++++if+is_a_color_word%28word%29+%7B%0A++++++++println%21%28%22That+is+a+color+word+I+know%21%22%29%3B%0A++++%7D+else+%7B%0A++++++++println%21%28%22That+is+not+a+color+word+I+know.%22%29%3B%0A++++%7D%0A%7D%0A%0Afn+is_a_color_word%28attempt%3A+%26str%29+-%3E+bool+%7B%0A++++attempt+%3D%3D+%22green%22+%7C%7C+attempt+%3D%3D+%22blue%22+%7C%7C+attempt+%3D%3D+%22red%22%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Yes%2C+it+would+be+really+easy+to+fix+this+by+just+changing+the+value+bound+to+%60word%60+to+be+a%0A%2F%2F+string+slice+instead+of+a+%60String%60%2C+wouldn%27t+it%3F%3F+There+is+a+way+to+add+one+character+to+line%0A%2F%2F+5%2C+though%2C+that+will+coerce+the+%60String%60+into+a+string+slice.%0A)
-- ["strings3.rs"](http://play.rust-lang.org/?code=%2F%2F+Ok%2C+here+are+a+bunch+of+values--+some+are+%60Strings%60%2C+some+are+%60%26strs%60.+Your%0A%2F%2F+task+is+to+call+one+of+these+two+functions+on+each+value+depending+on+what%0A%2F%2F+you+think+each+value+is.+That+is%2C+add+either+%60string_slice%60+or+%60string%60%0A%2F%2F+before+the+parentheses+on+each+line.+If+you%27re+right%2C+it+will+compile%21%0A%0Afn+string_slice%28arg%3A+%26str%29+%7B+println%21%28%22%7B%7D%22%2C+arg%29%3B+%7D%0Afn+string%28arg%3A+String%29+%7B+println%21%28%22%7B%7D%22%2C+arg%29%3B+%7D%0A%0Afn+main%28%29+%7B%0A++++%28%22blue%22%29%3B%0A++++%28%22red%22.to_string%28%29%29%3B%0A++++%28String%3A%3Afrom%28%22hi%22%29%29%3B%0A++++%28format%21%28%22Interpolation+%7B%7D%22%2C+%22Station%22%29%29%3B%0A++++%28%26String%3A%3Afrom%28%22abc%22%29%5B0..1%5D%29%3B%0A++++%28%22++hello+there+%22.trim%28%29%29%3B%0A++++%28%22Happy+Monday%21%22.to_string%28%29.replace%28%22Mon%22%2C+%22Tues%22%29%29%3B%0A++++%28%22mY+sHiFt+KeY+iS+sTiCkY%22.to_lowercase%28%29%29%3B%0A%7D%0A)
+- ["strings3.rs"](http://play.rust-lang.org/?code=%2F%2F+Ok%2C+here+are+a+bunch+of+values--+some+are+%60Strings%60%2C+some+are+%60%26strs%60.+Your%0A%2F%2F+task+is+to+call+one+of+these+two+functions+on+each+value+depending+on+what%0A%2F%2F+you+think+each+value+is.+That+is%2C+add+either+%60string_slice%60+or+%60string%60%0A%2F%2F+before+the+parentheses+on+each+line.+If+you%27re+right%2C+it+will+compile%21%0A%0Afn+string_slice%28arg%3A+%26str%29+%7B+println%21%28%22%7B%7D%22%2C+arg%29%3B+%7D%0Afn+string%28arg%3A+String%29+%7B+println%21%28%22%7B%7D%22%2C+arg%29%3B+%7D%0A%0Afn+main%28%29+%7B%0A++++%28%22blue%22%29%3B%0A++++%28%22red%22.to_string%28%29%29%3B%0A++++%28String%3A%3Afrom%28%22hi%22%29%29%3B%0A++++%28%22rust+is+fun%21%22.to_owned%28%29%29%3B%0A++++%28%22nice+weather%22.into%28%29%29%3B%0A++++%28format%21%28%22Interpolation+%7B%7D%22%2C+%22Station%22%29%29%3B%0A++++%28%26String%3A%3Afrom%28%22abc%22%29%5B0..1%5D%29%3B%0A++++%28%22++hello+there+%22.trim%28%29%29%3B%0A++++%28%22Happy+Monday%21%22.to_string%28%29.replace%28%22Mon%22%2C+%22Tues%22%29%29%3B%0A++++%28%22mY+sHiFt+KeY+iS+sTiCkY%22.to_lowercase%28%29%29%3B%0A%7D%0A)
 
 ### Move semantics
 
@@ -120,7 +120,7 @@ Check out the [Iterators chapter of the book](https://doc.rust-lang.org/stable/b
 
 See [the Dining Philosophers example](https://doc.rust-lang.org/1.4.0/book/dining-philosophers.html) and the [Concurrency Chapter](https://doc.rust-lang.org/stable/book/concurrency.html) from the book.
 
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 ### Uncategorized