Add append method to BLOCK

Refactorize code to re-utilize append method.

Author: boriel

src/symbols/block.py

@@ -24,17 +24,8 @@ def __init__(self, *nodes):
     def make_node(cls, *args):
         """ Creates a chain of code blocks.
         """
-        new_args = []
-
-        args = [x for x in args if not is_null(x)]
-        for x in args:
-            assert isinstance(x, Symbol)
-            if x.token == 'BLOCK':
-                new_args.extend(SymbolBLOCK.make_node(*x.children).children)
-            else:
-                new_args.append(x)
-
-        result = SymbolBLOCK(*new_args)
+        result = SymbolBLOCK()
+        result.append(*args)
         return result
 
     def __getitem__(self, item):
@@ -54,3 +45,13 @@ def __hash__(self):
 
     def pop(self, pos: int) -> Symbol:
         return self.children.pop(pos)
+
+    def append(self, *args):
+        for arg in args:
+            if check.is_null(arg):
+                continue
+            assert isinstance(arg, Symbol), f"Invalid argument '{arg}'"
+            if arg.token == 'BLOCK':
+                self.append(*arg.children)
+            else:
+                self.children.append(arg)