diff --git a/docs/TODO.txt b/docs/TODO.txt
index fb01944..546d960 100644
--- a/docs/TODO.txt
+++ b/docs/TODO.txt
@@ -27,22 +27,20 @@ DONE: native functions
 DONE: global functions _get, _set, _push, _pop, _length, clear available
 DONE: change comma to colon in dictionary definition
 DONE: Address circular references
-TODO: are compounds shallow or deep copies? Deep copies
+DONE: are compounds shallow or deep copies? Deep copies
+DONE: third output stream, for lexer/parser/compiler/interpreter errors
+DONE: Assertion-based test scripts
 
 
-TODO: third output stream, for lexer/parser/compiler/interpreter errors
-
-
-TODO: slice and dot notation around the _index function
+TODO: Import/export keywords
+TODO: slice and dot notation around the builtin _index function
 TODO: ternary operator
-TODO: Nullish types
+TODO: Nullish types?
 TODO: A way to check the type of a variable (typeOf keyword)
 TODO: a = b = c = 1; ?
-TODO: Assertion-based test scripts
 TODO: standard library
-TODO: external runner library
-TODO: document how it all works
-TODO: better and more consistent error messages
+TODO: external script runner library
+TODO: document how it all works - book?
 TODO: maximum recursion/function depth
 
 
diff --git a/source/compiler.c b/source/compiler.c
index 4bc01fb..7654102 100644
--- a/source/compiler.c
+++ b/source/compiler.c
@@ -184,7 +184,7 @@ static int writeNodeCompoundToCache(Compiler* compiler, Node* node) {
 		freeLiteral(literal);
 	}
 	else {
-		fprintf(stderr, ERROR "[Internal] Unrecognized compound type in writeNodeCompoundToCache()" RESET);
+		fprintf(stderr, ERROR "[internal] Unrecognized compound type in writeNodeCompoundToCache()" RESET);
 	}
 
 	return index;
@@ -279,7 +279,7 @@ static void writeCompilerWithJumps(Compiler* compiler, Node* node, void* breakAd
 	//determine node type
 	switch(node->type) {
 		case NODE_ERROR: {
-			fprintf(stderr, ERROR "[Internal] NODE_ERROR encountered in writeCompilerWithJumps()\n" RESET);
+			fprintf(stderr, ERROR "[internal] NODE_ERROR encountered in writeCompilerWithJumps()\n" RESET);
 			compiler->bytecode[compiler->count++] = OP_EOF; //1 byte
 		}
 		break;
@@ -338,7 +338,7 @@ static void writeCompilerWithJumps(Compiler* compiler, Node* node, void* breakAd
 		break;
 
 		case NODE_PAIR:
-			fprintf(stderr, ERROR "[Internal] NODE_PAIR encountered in writeCompilerWithJumps()\n" RESET);
+			fprintf(stderr, ERROR "[internal] NODE_PAIR encountered in writeCompilerWithJumps()\n" RESET);
 		break;
 
 		case NODE_VAR_DECL: {
diff --git a/source/lexer.c b/source/lexer.c
index 6105f24..5b20ce5 100644
--- a/source/lexer.c
+++ b/source/lexer.c
@@ -308,6 +308,7 @@ static void trim(char** s, int* l) { //all this to remove a newline?
 	while(**s && isspace( **(unsigned char**)(s)) ) { (*s)++; (*l)--; }
 }
 
+//for debugging
 void printToken(Token* token) {
 	if (token->type == TOKEN_ERROR) {
 		printf(ERROR "Error\t%d\t%.*s\n" RESET, token->line, token->length, token->lexeme);
diff --git a/source/lexer.h b/source/lexer.h
index 74595a4..3211502 100644
--- a/source/lexer.h
+++ b/source/lexer.h
@@ -22,4 +22,5 @@ typedef struct {
 void initLexer(Lexer* lexer, char* source);
 Token scanLexer(Lexer* lexer);
 
+//for debugging
 void printToken(Token* token);
\ No newline at end of file
diff --git a/test/test_interpreter.c b/test/test_interpreter.c
index f2df14e..89d0c8a 100644
--- a/test/test_interpreter.c
+++ b/test/test_interpreter.c
@@ -11,7 +11,12 @@
 #include <stdlib.h>
 #include <string.h>
 
-//IO functions
+//supress the print output
+static void noPrintFn(const char* output) {
+	//NO OP
+}
+
+//compilation functions
 char* readFile(char* path, size_t* fileSize) {
 	FILE* file = fopen(path, "rb");
 
@@ -86,6 +91,10 @@ unsigned char* compileString(char* source, size_t* size) {
 void runBinary(unsigned char* tb, size_t size) {
 	Interpreter interpreter;
 	initInterpreter(&interpreter);
+
+	//NOTE: supress print output for testing
+	setInterpreterPrint(&interpreter, noPrintFn);
+
 	runInterpreter(&interpreter, tb, size);
 	freeInterpreter(&interpreter);
 }
@@ -138,6 +147,9 @@ int main() {
 		int size = 0;
 		unsigned char* bytecode = collateCompiler(&compiler, &size);
 
+		//NOTE: supress print output for testing
+		setInterpreterPrint(&interpreter, noPrintFn);
+
 		//run
 		runInterpreter(&interpreter, bytecode, size);