nd some potential typos.
# &#x89E3;&#x6C7A;&#x306E;&#x30D2;&#x30F3;&#x30C8;: &#x30EC;&#x30B3;&#x30FC;&#x30C9;&#x306E;&#x30D5;&#x30A3;&#x30FC;&#x30EB;&#x30C9;&#x3092;&#x6BD4;&#x3079;&#x305F;&#x3068;&#x3053;&#x308D;&#x3001;typo&#x3089;&#x3057;&#x304D;&#x3082;&#x306E;&#x304C;&#x898B;&#x3064;&#x304B;&#x308A;&#x307E;&#x3057;&#x305F;&#x3002;

    firstName &lt;-&gt; fistName
</code></pre><!--
It sees that `toFullName` is getting the wrong _type_ of argument. Like the hint in the error message says, someone accide