added Graphviz visualizations

src/runtime/python/pgf.pyi

@@ -114,7 +114,7 @@ class PGF:
         """
         ...
 
-    def generateRandom(cat : Type, depth : int = 5) -> tuple[Expr,float]:
+    def generateRandom(self, cat : Type, depth : int = 5) -> tuple[Expr,float]:
         """
         Generates a random abstract syntax trees of the given type.
         The depth parameter specifies the maximal distance between
@@ -123,6 +123,16 @@ class PGF:
         """
         ...
 
+    def graphvizAbstractTree(self, e: Expr,
+                             noFun:bool=False, noCat:bool=False,
+                             nodeFont:str="",
+                             nodeColor:str="",
+                             nodeEdgeStyle:str="") -> str:
+        """
+        Renders an abstract syntax tree in a Graphviz format
+        """
+        ...
+
     def newTransaction(self) -> Transaction:
         """
         Starts a new transaction which makes it possible to update
@@ -208,11 +218,11 @@ class Concr:
         """The name of the concrete syntax"""
         ...
 
-    def linearize(e: Expr) -> str:
+    def linearize(self, e: Expr) -> str:
         """Linearizes the abstract expression and returns as string"""
         ...
 
-    def bracketedLinearize(e: Expr) -> list[Any]:
+    def bracketedLinearize(self, e: Expr) -> list[Any]:
         """
         Produces a bracketed linearization where syntactic phrases
         are represented as objects of type Bracket and terminal tokens
@@ -221,6 +231,22 @@ class Concr:
         """
         ...
 
+    def hasLinearization(self, fun: Str) -> bool:
+        """
+        Returns true if the given function has linearization in the concrete syntax
+        """
+        ...
+
+    def graphvizParseTree(self, e: Expr,
+                          noLeaves:bool=False, noFun:bool=False, noCat:bool=False,
+                          nodeFont:str="", leafFont:str="",
+                          nodeColor:str="", leafColor:str="",
+                          nodeEdgeStyle:str="", leafEdgeStyle:str="") -> str:
+        """
+        Renders an abstract syntax tree as a parse tree in Graphviz format
+        """
+        ...
+
 class PGFError:
     """
     This is the exception that several functions throw