diff --git a/dopey.py b/dopey.py
index d07f36d..3dc9341 100755
--- a/dopey.py
+++ b/dopey.py
@@ -11,9 +11,9 @@ class MemoryException(Exception):
     """ TODO line number and column """
     pass
 
-class Memory:
+class _Memory:
     BUFFER_SIZE = 30_000
-    buffer = [0 for _ in range(BUFFER_SIZE)]
+    buffer = []
     pointer = 0
     input_buffer = []
 
@@ -21,7 +21,13 @@ class Memory:
     def get_pointer(cls) -> int:
         return cls.pointer
 
-class Operation:
+    @classmethod
+    def reset(cls):
+        cls.buffer = [0 for _ in range(cls.BUFFER_SIZE)]
+        cls.pointer = 0
+        cls.input_buffer = []
+
+class _Operation:
     SHIFT_LEFT = "<"
     SHIFT_RIGHT = ">"
     INCREMENT = "+"
@@ -41,49 +47,49 @@ class Operation:
             return
 
         # dont perform any non loop operations if inside an ignore loop
-        if len(cls.loop_ignore_stack) and operation != Operation.CLOSE_LOOP and operation != Operation.OPEN_LOOP:
+        if len(cls.loop_ignore_stack) and operation != _Operation.CLOSE_LOOP and operation != _Operation.OPEN_LOOP:
             return
 
         switch[operation](program)
 
     @classmethod
     def shift_left(cls, _) -> None:
-        Memory.pointer -= 1
-        if Memory.pointer < 0:
+        _Memory.pointer -= 1
+        if _Memory.pointer < 0:
             raise MemoryException
     
     @classmethod
     def shift_right(cls, _) -> None:
-        Memory.pointer += 1
-        if Memory.pointer >= Memory.BUFFER_SIZE:
+        _Memory.pointer += 1
+        if _Memory.pointer >= _Memory.BUFFER_SIZE:
             raise MemoryException
 
     @classmethod    
     def increment(cls, _) -> None:
-        Memory.buffer[Memory.get_pointer()] += 1
+        _Memory.buffer[_Memory.get_pointer()] += 1
 
     @classmethod
     def decrement(cls, _) -> None:
-        Memory.buffer[Memory.get_pointer()] -= 1
+        _Memory.buffer[_Memory.get_pointer()] -= 1
 
     @classmethod
     def output(cls, _) -> None:
-        sys.stdout.write(chr(Memory.buffer[Memory.get_pointer()])) # TODO rollover if too big in ASCII
+        sys.stdout.write(chr(_Memory.buffer[_Memory.get_pointer()])) # TODO rollover if too big in ASCII
         sys.stdout.flush() # TODO possible performance issue
 
     @classmethod
     def input(cls, _) -> None:
-        if not len(Memory.input_buffer):
+        if not len(_Memory.input_buffer):
             input_ = sys.stdin.readline()
-            Memory.input_buffer += list(input_)
-        if len(Memory.input_buffer):
-            Memory.buffer[Memory.get_pointer()] = ord(Memory.input_buffer.pop(0))
+            _Memory.input_buffer += list(input_)
+        if len(_Memory.input_buffer):
+            _Memory.buffer[_Memory.get_pointer()] = ord(_Memory.input_buffer.pop(0))
 
     @classmethod
     def open_loop(cls, program: List) -> None:
-        if not Memory.buffer[Memory.get_pointer()]:
+        if not _Memory.buffer[_Memory.get_pointer()]:
             # enter ignore loop if byte at pointer is zero
-            cls.loop_ignore_stack.append(Operation.OPEN_LOOP)
+            cls.loop_ignore_stack.append(_Operation.OPEN_LOOP)
         else:
             # save start loop position should we need to return
             cls.loop_stack.append(program[1]-1)
@@ -101,7 +107,7 @@ class Operation:
 
         # check if we need to repeat
         last_open_loop_pos = cls.loop_stack.pop()
-        if Memory.buffer[Memory.get_pointer()]:
+        if _Memory.buffer[_Memory.get_pointer()]:
             program[1] = last_open_loop_pos
 
     @classmethod
@@ -117,6 +123,24 @@ class Operation:
             cls.CLOSE_LOOP: cls.close_loop
         }
 
+class Interpreter:
+    def __init__(self):
+        pass
+
+    def execute(self, str_program: str) -> None:
+        _Memory.reset()
+
+        program = [str_program, 0] # TODO create program class
+        switch = _Operation.get_operations_in_switch()
+
+        while program[1] < len(program[0]):
+            operation = program[0][program[1]]
+            program[1] += 1
+            _Operation.perform(operation, program, switch)
+
+        if len(_Operation.loop_stack):
+            raise MismatchBracketException
+
 def main() -> None:
     file_location = None
     if len(sys.argv) != 2:
@@ -126,18 +150,11 @@ def main() -> None:
         file_location = sys.argv[1]
 
     file = open(file_location, "r")
-    program = [file.read(), 0] # TODO create program class
+    str_program = file.read()
     file.close()
 
-    switch = Operation.get_operations_in_switch()
-    while program[1] < len(program[0]):
-        operation = program[0][program[1]]
-        program[1] += 1
-        Operation.perform(operation, program, switch)
-
-    if len(Operation.loop_stack):
-        raise MismatchBracketException
+    interpreter = Interpreter()
+    interpreter.execute(str_program)
 
 if __name__ == "__main__":
-    main()
-
+    main()
\ No newline at end of file