diff --git a/jedi/parser/pytree.py b/jedi/parser/pytree.py
index 2d91fc2d..3c968bfe 100644
--- a/jedi/parser/pytree.py
+++ b/jedi/parser/pytree.py
@@ -46,9 +46,9 @@ del python_grammar_no_print_statement.keywords["print"]
 
 from jedi.parser.representation import ExprStmt, Class, Function
 _ast_mapping = {
-    'simple_stmt': ExprStmt,
+    #'simple_stmt': ExprStmt,
     'classdef': Class,
-    'funcdef': Function
+    'funcdef': Function,
 }
 
 ast_mapping = dict((getattr(python_symbols, k), v) for k, v in _ast_mapping.items())
@@ -79,7 +79,6 @@ class Base(object):
     # Default values for instance variables
     type = None    # int: token number (< 256) or symbol number (>= 256)
     parent = None  # Parent node pointer, or None
-    children = ()  # Tuple of subnodes
 
     def leaves(self):
         for child in self.children:
@@ -134,6 +133,14 @@ class Node(Base):
             return ""
         return self.children[0].prefix
 
+    @property
+    def start_pos(self):
+        return self.children[0].start_pos
+
+    @property
+    def end_pos(self):
+        return self.children[-1].end_pos
+
     @prefix.setter
     def prefix(self, prefix):
         if self.children:
@@ -172,6 +179,10 @@ class Leaf(Base):
         self.type = type
         self.value = value
 
+    @property
+    def end_pos(self):
+        return self.start_pos[0], self.start_pos[1] + len(self.value)
+
     def __repr__(self):
         """Return a canonical string representation."""
         return "%s(%r, %r)" % (self.__class__.__name__,
diff --git a/jedi/parser/representation.py b/jedi/parser/representation.py
index e9575fef..1ff9d7d9 100644
--- a/jedi/parser/representation.py
+++ b/jedi/parser/representation.py
@@ -173,7 +173,7 @@ class Simple(Base):
     The super class for Scope, Import, Name and Statement. Every object in
     the parser tree inherits from this class.
     """
-    __slots__ = ('children',)
+    __slots__ = ('children', 'parent')
 
     def __init__(self, children):
         """
@@ -183,6 +183,7 @@ class Simple(Base):
         :param children: The module in which this Python object locates.
         """
         self.children = children
+        self.parent = None
 
     @property
     def start_pos(self):
@@ -238,8 +239,8 @@ class Scope(Simple, DocstringMixin):
     __slots__ = ('subscopes', 'imports', 'statements', '_doc_token', 'asserts',
                  'returns', 'is_generator', '_names_dict')
 
-    def __init__(self, module, start_pos):
-        super(Scope, self).__init__(module, start_pos)
+    def __init__(self, children):
+        super(Scope, self).__init__(children)
         self.subscopes = []
         self.imports = []
         self.statements = []
@@ -549,30 +550,25 @@ class Function(Scope):
     :param start_pos: The start position (line, column) the Function.
     :type start_pos: tuple(int, int)
     """
-    __slots__ = ('name', 'params', 'decorators', 'listeners', 'annotation')
+    __slots__ = ('decorators', 'listeners')
 
-    def __init__(self, module, name, params, start_pos, annotation):
-        super(Function, self).__init__(module, start_pos)
-        self.name = name
-        if name is not None:
-            name.parent = self.use_as_parent
-        self.params = params
-        for p in params:
-            p.parent = self.use_as_parent
-            p.parent_function = self.use_as_parent
+    def __init__(self, children):
+        super(Function, self).__init__(children)
         self.decorators = []
         self.listeners = set()  # not used here, but in evaluation.
 
-        if annotation is not None:
-            annotation.parent = self.use_as_parent
-        self.annotation = annotation
+    @property
+    def name(self):
+        return self.children[1]  # First token after `def`
 
-    def get_code(self, first_indent=False, indention='    '):
-        string = "\n".join('@' + stmt.get_code() for stmt in self.decorators)
-        params = ', '.join([stmt.get_code(False) for stmt in self.params])
-        string += "def %s(%s):\n" % (self.name, params)
-        string += super(Function, self).get_code(True, indention)
-        return string
+    def params(self):
+        return self.children[3].children  # After def foo(
+
+    def annotation(self):
+        try:
+            return self.children[6]  # 6th element: def foo(...) -> bar
+        except IndexError:
+            return None
 
     def get_defined_names(self):
         n = super(Function, self).get_defined_names()
diff --git a/test/test_new_parser.py b/test/test_new_parser.py
index 8910c0be..8d289d9f 100644
--- a/test/test_new_parser.py
+++ b/test/test_new_parser.py
@@ -19,7 +19,7 @@ def test_basic():
     print(repr(tree))
     print(tree)
     #import pdb; pdb.set_trace()
-    print(repr(d.parse_string('def x(): pass\n')))
+    print(repr(d.parse_string('def x(a, b:3): pass\n')))
     print()
     x = d.parse_string('\na #pass\n')
     print(repr(x))