diff --git a/.github/pull_request_template.md b/.github/pull_request_template.md
new file mode 100644
index 0000000..ee8b7ee
--- /dev/null
+++ b/.github/pull_request_template.md
@@ -0,0 +1,37 @@
+## Pull Request Template
+
+### Description
+
+[ description of the bug fix or new functionality ]
+
+[ include directions for reviewers if necessary- what or how should they test or review ]
+
+Fixes # (issue(s))
+
+### Corresponding branches and PRs:
+
+[ which branches of wex, lk, and ssc should be built with this PR ]
+
+[ link any corresponding PRs in other repos, i.e. NREL/ssc#x ]
+
+### Unit Test Impact:
+
+[ new tests written? ]
+
+[ expected changes in unit tests or speed of tests? ]
+
+[ expected changes in test_results files? ]
+
+### Checklist
+- [ ] requires help revision and I added that label
+- [ ] adds, removes, modifies, or deletes variables in existing compute modules
+- [ ] adds a new compute module
+- [ ] changes defaults
+- [ ] I've tagged this PR to a milestone
+
+### Reminders- this section can be deleted
+[Checking for PySAM Incompatible API Changes]
+(https://github.com/NREL/SAM/wiki/PySAM-Incompatible-API-Changes-&-Regenerating-PySAM-Files).
+
+[When do the PySAM files need to be regenerated?]
+(https://github.com/NREL/SAM/wiki/PySAM-Incompatible-API-Changes-&-Regenerating-PySAM-Files#when-do-the-pysam-files-need-to-be-regenerated-via-export_config)
diff --git a/src/stdlib.cpp b/src/stdlib.cpp
index 1e8fdc1..109bc20 100644
--- a/src/stdlib.cpp
+++ b/src/stdlib.cpp
@@ -1862,19 +1862,55 @@ static void _ascii(lk::invoke_t &cxt) {
 static void _isalpha(lk::invoke_t &cxt) {
     LK_DOC("isalpha", "Returns true if the argument is an alphabetic character A-Z,a-z.", "(character):boolean");
     lk_string s = cxt.arg(0).as_string();
-    cxt.result().assign(::isalpha(s.length() > 0 ? (int) s[0] : 0) ? 1.0 : 0.0);
+    double x = 0;
+    if (!s.IsNull()) {
+        try {
+            lk_char y = s[0];
+            if (y < 256 && !s.IsNull())
+                x = ::isalpha(s.length() > 0 ? (int)y : 0) ? 1.0 : 0.0;
+        }
+        catch (const std::exception&) {
+            x = 0;
+        }
+    }
+    cxt.result().assign(x);
+    //cxt.result().assign(::isalpha(s.length() > 0 ? (int) s[0] : 0) ? 1.0 : 0.0);
 }
 
 static void _isdigit(lk::invoke_t &cxt) {
     LK_DOC("isdigit", "Returns true if the argument is a numeric digit 0-9.", "(character):boolean");
     lk_string s = cxt.arg(0).as_string();
-    cxt.result().assign(::isdigit(s.length() > 0 ? (int) s[0] : 0) ? 1.0 : 0.0);
+    double x = 0;
+    if (!s.IsNull()) {
+        try {
+            lk_char y = s[0];
+            if (y < 256)
+                x = ::isdigit(s.length() > 0 ? (int)y : 0) ? 1.0 : 0.0;
+        }
+        catch (const std::exception&) {
+            x = 0;
+        }
+    }
+    cxt.result().assign(x);
+//    cxt.result().assign(::isdigit(s.length() > 0 ? (int) s[0] : 0) ? 1.0 : 0.0);
 }
 
-static void _isalnum(lk::invoke_t &cxt) {
+static void _isalnum(lk::invoke_t& cxt) {
     LK_DOC("isalnum", "Returns true if the argument is an alphanumeric A-Z,a-z,0-9.", "(character):boolean");
     lk_string s = cxt.arg(0).as_string();
-    cxt.result().assign(::isalnum(s.length() > 0 ? (int) s[0] : 0) ? 1.0 : 0.0);
+    double x = 0;
+    if (!s.IsNull()) {
+        try {
+            lk_char y = s[0];
+            if (y < 256)
+                x = ::isalnum(s.length() > 0 ? (int)y : 0) ? 1.0 : 0.0;
+        }
+        catch (const std::exception&) {
+            x = 0;
+        }
+    }
+    cxt.result().assign(x);
+ //   cxt.result().assign(::isalnum(s.length() > 0 ? (int) s[0] : 0) ? 1.0 : 0.0);
 }
 
 static void _char(lk::invoke_t &cxt) {