diff --git a/examples/01-blog/Blog/Type/Scalar/EmailType.php b/examples/01-blog/Blog/Type/Scalar/EmailType.php
index 9800ba4..d7541ea 100644
--- a/examples/01-blog/Blog/Type/Scalar/EmailType.php
+++ b/examples/01-blog/Blog/Type/Scalar/EmailType.php
@@ -1,6 +1,7 @@
 <?php
 namespace GraphQL\Examples\Blog\Type\Scalar;
 
+use GraphQL\Error\Error;
 use GraphQL\Examples\Blog\Type\BaseType;
 use GraphQL\Language\AST\StringValue;
 use GraphQL\Type\Definition\CustomScalarType;
@@ -22,26 +23,26 @@ class EmailType extends BaseType
     /**
      * Serializes an internal value to include in a response.
      *
-     * @param mixed $value
-     * @return mixed
+     * @param string $value
+     * @return string
      */
     public function serialize($value)
     {
-        return $this->coerceEmail($value);
+        // Assuming internal representation of email is always correct:
+        return $value;
+
+        // If it might be incorrect and you want to make sure that only correct values are included in response -
+        // use following line instead:
+        // return $this->parseValue($value);
     }
 
     /**
-     * Parses an externally provided value to use as an input
+     * Parses an externally provided value (query variable) to use as an input
      *
      * @param mixed $value
      * @return mixed
      */
     public function parseValue($value)
-    {
-        return $this->coerceEmail($value);
-    }
-
-    private function coerceEmail($value)
     {
         if (!filter_var($value, FILTER_VALIDATE_EMAIL)) {
             throw new \UnexpectedValueException("Cannot represent value as email: " . Utils::printSafe($value));
@@ -50,16 +51,22 @@ class EmailType extends BaseType
     }
 
     /**
-     * Parses an externally provided literal value to use as an input
+     * Parses an externally provided literal value (hardcoded in GraphQL query) to use as an input
      *
-     * @param \GraphQL\Language\AST\Value $valueAST
-     * @return mixed
+     * @param \GraphQL\Language\AST\Node $valueAST
+     * @return string
+     * @throws Error
      */
     public function parseLiteral($valueAST)
     {
-        if ($valueAST instanceof StringValue) {
-            return $valueAST->value;
+        // Note: throwing GraphQL\Error\Error vs \UnexpectedValueException to benefit from GraphQL
+        // error location in query:
+        if (!$valueAST instanceof StringValue) {
+            throw new Error('Query error: Can only parse strings got: ' . $valueAST->kind, [$valueAST]);
         }
-        return null;
+        if (!filter_var($valueAST->value, FILTER_VALIDATE_EMAIL)) {
+            throw new Error("Not a valid email", [$valueAST]);
+        }
+        return $valueAST->value;
     }
 }
diff --git a/examples/01-blog/Blog/Type/Scalar/UrlType.php b/examples/01-blog/Blog/Type/Scalar/UrlType.php
index 675e38b..46c282e 100644
--- a/examples/01-blog/Blog/Type/Scalar/UrlType.php
+++ b/examples/01-blog/Blog/Type/Scalar/UrlType.php
@@ -1,6 +1,8 @@
 <?php
 namespace GraphQL\Examples\Blog\Type\Scalar;
 
+use GraphQL\Error\Error;
+use GraphQL\Language\AST\Node;
 use GraphQL\Language\AST\StringValue;
 use GraphQL\Type\Definition\ScalarType;
 use GraphQL\Utils;
@@ -17,25 +19,21 @@ class UrlType extends ScalarType
      */
     public function serialize($value)
     {
-        return $this->coerceUrl($value);
+        // Assuming internal representation of url is always correct:
+        return $value;
+
+        // If it might be incorrect and you want to make sure that only correct values are included in response -
+        // use following line instead:
+        // return $this->parseValue($value);
     }
 
     /**
-     * Parses an externally provided value to use as an input
+     * Parses an externally provided value (query variable) to use as an input
      *
      * @param mixed $value
      * @return mixed
      */
     public function parseValue($value)
-    {
-        return $this->coerceUrl($value);
-    }
-
-    /**
-     * @param $value
-     * @return float|null
-     */
-    private function coerceUrl($value)
     {
         if (!is_string($value) || !filter_var($value, FILTER_VALIDATE_URL)) { // quite naive, but after all this is example
             throw new \UnexpectedValueException("Cannot represent value as URL: " . Utils::printSafe($value));
@@ -44,13 +42,22 @@ class UrlType extends ScalarType
     }
 
     /**
+     * Parses an externally provided literal value to use as an input (e.g. in Query AST)
+     *
+     * @param $ast Node
      * @return null|string
+     * @throws Error
      */
     public function parseLiteral($ast)
     {
-        if ($ast instanceof StringValue) {
-            return $ast->value;
+        // Note: throwing GraphQL\Error\Error vs \UnexpectedValueException to benefit from GraphQL
+        // error location in query:
+        if (!($ast instanceof StringValue)) {
+            throw new Error('Query error: Can only parse strings got: ' . $ast->kind, [$ast]);
         }
-        return null;
+        if (!is_string($ast->value) || !filter_var($ast->value, FILTER_VALIDATE_URL)) {
+            throw new Error('Query error: Not a valid URL', [$ast]);
+        }
+        return $ast->value;
     }
 }