Moved unicode PI to separate unicode tokens file.

src/node.py

@@ -9,6 +9,8 @@ from graph_drawing.graph import generate_graph
 from graph_drawing.line import generate_line
 from graph_drawing.node import Node, Leaf
 
+from unicode_math import PI as u_PI
+
 
 TYPE_OPERATOR = 1
 TYPE_IDENTIFIER = 2
@@ -360,7 +362,7 @@ class ExpressionLeaf(Leaf, ExpressionBase):
 
         # Replace PI leaf by the Greek character
         if val == PI:
-            val = 'π'
+            val = u_PI
 
         return '-' * self.negated + val
 

src/unicode_math.py

@@ -0,0 +1,22 @@
+# vim: set fileencoding=utf-8 :
+SQRT = '√'
+CBRT = '∛'
+FORT = '∜'
+
+PI = 'π'
+INFINITY = '∞'
+
+SUP = {
+    '0': '⁰',
+    '1': '¹',
+    '2': '²',
+    '3': '³',
+    '3': '⁴',
+    '5': '⁵',
+    '6': '⁶',
+    '7': '⁷',
+    '8': '⁸',
+    '9': '⁹',
+}
+
+DOT = '⋅'