fix: lack space (source-academy#780)

Co-authored-by: xufeng <[email protected]>
yiwen101 · May 26, 2022 · ba71acc · ba71acc
1 parent 0a7f3ea
commit ba71acc
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/xml/chapter2/section3/subsection2.xml b/xml/chapter2/section3/subsection2.xml
@@ -1039,7 +1039,7 @@ function make_exp(base, exp) {
              : list("**", base, exp);
 }
 function is_exp(x) {
-    return is_pair(x) &amp;&amp; head(x) ==="**";
+    return is_pair(x) &amp;&amp; head(x) === "**";
 }
 function deriv(exp, variable) {
     return is_number(exp)