class HalfedgeMesh:
    def __init__(self, filename=None):
        """Make an empty halfedge mesh."""
        self.vertices = []
        self.halfedges = []
        self.facets = []

    def read_off(self, filename):

    class Vertex:
        def __init__(self, x, y, z, index):
            """Create a vertex with given index at given point.

            Args:
                x: x-coordinate of the point
                y: y-coordinate of the point
                z: z-coordinate of the point
                index: integer id of this vertex
            """
            pass

        def halfedges(self):
            """Return a list of halfedges targeting to this vertex."""
            pass

    class Facet:
        def __init__(self, index):
            """Create a facet with the given index."""
            pass

        def halfedges(self):
            """Return halfedges going ccw around this facet."""
            pass

    class Halfedge:
        def __init__(self, index):
            """Create a halfedge with given index."""
            pass
        def opposite(self):
            """Return the opposite halfedge."""
            pass

        def next(self):
            """Return the opposite halfedge."""
            pass

        def prev(self):
            """Return the opposite halfedge."""
            pass

        def vertex(self):
            """Return the target vertex."""
            pass

        def facet(self):
            """Return the incident facet."""
            pass


if __name__ == '__main__':
    m = HalfedgeMesh()

class HalfedgeMesh:
    def __init__(self, filename=None):
        """Make an empty halfedge mesh."""
        self.vertices = []
        self.halfedges = []
        self.facets = []

    def parse_off(self, filename):
        """Parses OFF files and returns a set of vertices, halfedges, and
        facets.
        """
        pass

    def get_halfedge(self, u, v):
        """Retrieve halfedge with starting vertex u and target vertex v

        u - starting vertex
        v - target vertex

        Returns a halfedge
        """
        pass

    class Vertex:
        def __init__(self, x, y, z, index):
            """Create a vertex with given index at given point.

            x     - x-coordinate of the point
            y     - y-coordinate of the point
            z     - z-coordinate of the point
            index - integer id of this vertex
            """
            pass

        def halfedges(self):
            """Return a list of halfedges targeting to this vertex."""
            pass

    class Facet:
        def __init__(self, index):
            """Create a facet with the given index."""
            pass

        def halfedges(self):
            """Return halfedges going ccw around this facet."""
            pass

    class Halfedge:
        def __init__(self, index):
            """Create a halfedge with given index."""
            pass
        def opposite(self):
            """Return the opposite halfedge."""
            pass

        def next(self):
            """Return the opposite halfedge."""
            pass

        def prev(self):
            """Return the opposite halfedge."""
            pass

        def vertex(self):
            """Return the target vertex."""
            pass

        def facet(self):
            """Return the incident facet."""
            pass


if __name__ == '__main__':
    m = HalfedgeMesh()

Add parse_off stub and change docstring
Add parse_off stub and change docstring

I follow the TomDoc format for docstrings.

  class HalfedgeMesh:
      def __init__(self, filename=None):
          """Make an empty halfedge mesh."""
          self.vertices = []
          self.halfedges = []
          self.facets = []
  
-     def read_off(self, filename):
+     def parse_off(self, filename):
+         """Parses OFF files and returns a set of vertices, halfedges, and
+         facets.
+         """
+         pass
+ 
+     def get_halfedge(self, u, v):
+         """Retrieve halfedge with starting vertex u and target vertex v
+ 
+         u - starting vertex
+         v - target vertex
+ 
+         Returns a halfedge
+         """
+         pass
  
      class Vertex:
          def __init__(self, x, y, z, index):
              """Create a vertex with given index at given point.
  
-             Args:
-                 x: x-coordinate of the point
+             x     - x-coordinate of the point
-                 y: y-coordinate of the point
+             y     - y-coordinate of the point
-                 z: z-coordinate of the point
+             z     - z-coordinate of the point
-                 index: integer id of this vertex
+             index - integer id of this vertex
              """
              pass
  
          def halfedges(self):
              """Return a list of halfedges targeting to this vertex."""
              pass
  
      class Facet:
          def __init__(self, index):
              """Create a facet with the given index."""
              pass
  
          def halfedges(self):
              """Return halfedges going ccw around this facet."""
              pass
  
      class Halfedge:
          def __init__(self, index):
              """Create a halfedge with given index."""
              pass
          def opposite(self):
              """Return the opposite halfedge."""
              pass
  
          def next(self):
              """Return the opposite halfedge."""
              pass
  
          def prev(self):
              """Return the opposite halfedge."""
              pass
  
          def vertex(self):
              """Return the target vertex."""
              pass
  
          def facet(self):
              """Return the incident facet."""
              pass
  
  
  if __name__ == '__main__':
      m = HalfedgeMesh()
  
Add parse_off stub and change docstring
## Code Before:
class HalfedgeMesh:
    def __init__(self, filename=None):
        """Make an empty halfedge mesh."""
        self.vertices = []
        self.halfedges = []
        self.facets = []

    def read_off(self, filename):

    class Vertex:
        def __init__(self, x, y, z, index):
            """Create a vertex with given index at given point.

            Args:
                x: x-coordinate of the point
                y: y-coordinate of the point
                z: z-coordinate of the point
                index: integer id of this vertex
            """
            pass

        def halfedges(self):
            """Return a list of halfedges targeting to this vertex."""
            pass

    class Facet:
        def __init__(self, index):
            """Create a facet with the given index."""
            pass

        def halfedges(self):
            """Return halfedges going ccw around this facet."""
            pass

    class Halfedge:
        def __init__(self, index):
            """Create a halfedge with given index."""
            pass
        def opposite(self):
            """Return the opposite halfedge."""
            pass

        def next(self):
            """Return the opposite halfedge."""
            pass

        def prev(self):
            """Return the opposite halfedge."""
            pass

        def vertex(self):
            """Return the target vertex."""
            pass

        def facet(self):
            """Return the incident facet."""
            pass


if __name__ == '__main__':
    m = HalfedgeMesh()

## Instruction:
Add parse_off stub and change docstring
## Code After:
class HalfedgeMesh:
    def __init__(self, filename=None):
        """Make an empty halfedge mesh."""
        self.vertices = []
        self.halfedges = []
        self.facets = []

    def parse_off(self, filename):
        """Parses OFF files and returns a set of vertices, halfedges, and
        facets.
        """
        pass

    def get_halfedge(self, u, v):
        """Retrieve halfedge with starting vertex u and target vertex v

        u - starting vertex
        v - target vertex

        Returns a halfedge
        """
        pass

    class Vertex:
        def __init__(self, x, y, z, index):
            """Create a vertex with given index at given point.

            x     - x-coordinate of the point
            y     - y-coordinate of the point
            z     - z-coordinate of the point
            index - integer id of this vertex
            """
            pass

        def halfedges(self):
            """Return a list of halfedges targeting to this vertex."""
            pass

    class Facet:
        def __init__(self, index):
            """Create a facet with the given index."""
            pass

        def halfedges(self):
            """Return halfedges going ccw around this facet."""
            pass

    class Halfedge:
        def __init__(self, index):
            """Create a halfedge with given index."""
            pass
        def opposite(self):
            """Return the opposite halfedge."""
            pass

        def next(self):
            """Return the opposite halfedge."""
            pass

        def prev(self):
            """Return the opposite halfedge."""
            pass

        def vertex(self):
            """Return the target vertex."""
            pass

        def facet(self):
            """Return the incident facet."""
            pass


if __name__ == '__main__':
    m = HalfedgeMesh()
