Implement USE

SMILEBASIC/error.d

@@ -2,6 +2,8 @@ module otya.smilebasic.error;
 import std.exception;
 import std.string;
 import std.conv;
+import otya.smilebasic.token;
+
 class SmileBasicError : Exception
 {
     int errnum;
@@ -154,6 +156,14 @@ class DuplicateVariable : SmileBasicError
         super("Duplicate variable");
     }
 }
+class DuplicateFunction : SmileBasicError
+{
+    this(int slot, SourceLocation loc)
+    {
+        this.errnum = 19;
+        super(slot, loc.line, "Duplicate function");
+    }
+}
 class ReturnWithoutGosub : SmileBasicError
 {
     this()