div class='output co'>#&gt; [1] "ThisIsAStrangeString" "AndThisAnotherOne"    NA                    </div><div class='input'><span class='fu'>to_screaming_snake_case</span>(<span class='no'>strings</span>)</div><div class='output co'>#&gt; [1] "THIS_IS_A_STRANGE_STRING" "AND_THIS_ANOTHER_ONE"    
#&gt; [3] NA                        </div><div class='input'><span class='fu'>to_lower_upper_case</span>(<span class='no'>strings</span>)</div><div class='output co'>#&gt; [1] "thisISaSTRANGEstring" "andTHISanother