diff --git a/ziffers/classes.py b/ziffers/classes.py
index 3ba4d4f..1a241a4 100644
--- a/ziffers/classes.py
+++ b/ziffers/classes.py
@@ -112,6 +112,7 @@ class Chord(Event):
         """Set notes to the class"""
         self.notes = notes
 
+
 @dataclass
 class RomanNumeral(Event):
     """Class for roman numbers"""
@@ -228,17 +229,25 @@ class Ziffers(Sequence):
             key = self.options["key"]
             scale = self.options["scale"]
             if isinstance(self.current, (Pitch, RandomPitch)):
-                note = note_from_pc(root=key,pitch_class=self.current.pitch_class,intervals=scale,modifier=self.current.modifier)
+                note = note_from_pc(
+                    root=key,
+                    pitch_class=self.current.pitch_class,
+                    intervals=scale,
+                    modifier=self.current.modifier,
+                )
                 self.current.set_note(note)
-            elif isinstance(self.current,Chord):
+            elif isinstance(self.current, Chord):
                 pcs = self.current.pitch_classes
-                notes = [pc.set_note(note_from_pc(key, pc.pitch_class, scale)) for pc in pcs]
+                notes = [
+                    pc.set_note(note_from_pc(key, pc.pitch_class, scale)) for pc in pcs
+                ]
                 self.current.set_notes(notes)
-            elif isinstance(self.current,RomanNumeral):
-                pitch_classes = [midi_to_pitch_class(note, key, scale) for note in self.current.notes]
+            elif isinstance(self.current, RomanNumeral):
+                pitch_classes = [
+                    midi_to_pitch_class(note, key, scale) for note in self.current.notes
+                ]
                 self.current.set_pitch_classes(pitch_classes)
 
-
         self.loop_i += 1
         return self.current
 
@@ -342,13 +351,13 @@ class Cyclic(Sequence):
     wrap_end: str = field(default=">", repr=False)
 
     def __next__(self):
-        yield self.values[self.cycle%len(self.cycle)]
-        self.cycle+=1
+        yield self.values[self.cycle % len(self.cycle)]
+        self.cycle += 1
         raise StopIteration
 
     def value(self):
         """Get the value for the current cycle"""
-        return self.values[self.cycle%len(self.cycle)]
+        return self.values[self.cycle % len(self.cycle)]
 
 
 @dataclass
diff --git a/ziffers/mapper.py b/ziffers/mapper.py
index 40953d8..587ca54 100644
--- a/ziffers/mapper.py
+++ b/ziffers/mapper.py
@@ -37,7 +37,7 @@ from .scale import parse_roman, chord_from_roman_numeral
 class ZiffersTransformer(Transformer):
     """Rules for transforming Ziffers expressions into tree."""
 
-    def __init__(self, options: Optional[dict]=None):
+    def __init__(self, options: Optional[dict] = None):
         super().__init__()
         self.options = options
 
@@ -114,21 +114,27 @@ class ZiffersTransformer(Transformer):
         """Parses chord"""
         return Chord(pitch_classes=items, text="".join([val.text for val in items]))
 
-    def named_roman(self,items) -> RomanNumeral:
+    def named_roman(self, items) -> RomanNumeral:
         """Parse chord from roman numeral"""
         numeral = items[0].value
-        if len(items)>1:
+        if len(items) > 1:
             name = items[1]
-            chord_notes = chord_from_roman_numeral(numeral,name)
+            chord_notes = chord_from_roman_numeral(numeral, name)
             parsed_number = parse_roman(numeral)
-            return RomanNumeral(text=numeral, value=parsed_number, chord_type=name, notes=chord_notes)
-        return RomanNumeral(value=parse_roman(numeral), text=numeral, notes=chord_from_roman_numeral(numeral))
+            return RomanNumeral(
+                text=numeral, value=parsed_number, chord_type=name, notes=chord_notes
+            )
+        return RomanNumeral(
+            value=parse_roman(numeral),
+            text=numeral,
+            notes=chord_from_roman_numeral(numeral),
+        )
 
-    def chord_name(self,item):
+    def chord_name(self, item):
         """Return name for chord"""
         return item[0].value
 
-    def roman_number(self,item):
+    def roman_number(self, item):
         """Return roman numeral"""
         return item.value
 
@@ -147,7 +153,7 @@ class ZiffersTransformer(Transformer):
                 val = val * (2.0 - (1.0 / (2 * dots)))
             chars = chars + (dchar + "." * dots)
             durs = durs + val
-        return {"text":chars, "duration":durs}
+        return {"text": chars, "duration": durs}
 
     def dchar_not_prefix(self, items):
         """Return partial duration char info"""
@@ -222,9 +228,13 @@ class ZiffersTransformer(Transformer):
         val = items[0]
         return Eval(values=val)
 
+    def sub_operations(self, items):
+        """Returns list of operations"""
+        return Eval(values=items[0], wrap_start="(", wrap_end=")")
+
     def operation(self, items):
         """Return partial eval operations"""
-        return items
+        return flatten(items)
 
     def atom(self, token):
         """Return partial eval item"""
diff --git a/ziffers/ziffers.lark b/ziffers/ziffers.lark
index e2c0f28..fe81493 100644
--- a/ziffers/ziffers.lark
+++ b/ziffers/ziffers.lark
@@ -18,7 +18,7 @@
     ?roman_number: /iv|v|v?i{1,3}/
   
     // Valid as integer
-    ?number: SIGNED_NUMBER | random_integer | cyclic_number
+    ?number: NUMBER | random_integer | cyclic_number
     cyclic_number: "<" number (WS number)* ">"
 
     // Repeats
@@ -69,11 +69,12 @@
 
     // Rules for evaluating clauses inside {}
     // TODO: Support for parenthesis?
-    eval: "{" operation "}"
-    operation: atom (operator atom)+  
-    atom: (number | DECIMAL)
+    eval: "{" operation+ "}"
+    operation: atom (operator (sub_operations | operation))*
+    sub_operations: "(" operation ")"
+    atom: (NUMBER | DECIMAL)
 
     %import common.NUMBER
-    %import common.SIGNED_NUMBER
+    //%import common.SIGNED_NUMBER
     %import common.DECIMAL
     %import common.WS
\ No newline at end of file