Manage the edges of the document.

Add an edge, defined by two vertices, in the document:

`edge_12 = doc.addEdge(vertex_1, vertex_2)`

Add an edge, defined by one vertex and one vector, in the document:

`edge_12 = doc.addEdgeVector(vertex, vector)`

Get the number of all edges in the document:

`sum_a = doc.countEdge()`

Get the number of edges used only in the model of blocks:

`sum_u = doc.countUsedEdge()`

Get the edges used by the model of blocks

```
# -*- coding: latin-1 -*-
# Copyright (C) 2009-2016 CEA/DEN, EDF R&D
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
# See http://www.salome-platform.org/ or email : webmaster.salome@opencascade.com
#
used_edges = []
for i in xrange( doc.countUsedEdge() ):
edge_i = doc.getUsedEdge(i)
used_edges.append(edge_i)
```

Get an edge of the document:

`edge_i = doc.getEdge(i)`

Get the vertices of an edge:

```
vertex_a = edge_i.getVertex(0)
vertex_b = edge_i.getVertex(1)
```

Find an edge in the document:

`edge_f = doc.findEdge(vertex_1, vertex_2)`

More operations: *Edge* inherits *Element*.

GUI command: *Edge*