def hedgesSharedByFace(f):
    """
    This function lists the *Half Edges* that delimit a specified face.
    Each face has an associated *HEdge* object that is one of the 3 
    *Half Edges* delimiting it.
    Each *HEdge* object points to the next *HEdge* object on the same 
    face, so we just follow this chain around until we get back to the 
    starting point.  
    
    .. image:: ../images/face.png
       :alt: HEdges shared by a single face

    Parameters
    ----------
   
    f:     
      *Face*.  The face to be scanned.
    """

    hEdgesShared = []
    startHEdge = f.he_hedge
    hEdgesShared.append(startHEdge)
    loopHedge = startHEdge.next
    x = 0
    if loopHedge:
        while loopHedge != startHEdge and x < 2:
            hEdgesShared.append(loopHedge)
            loopHedge = loopHedge.next
            x += 1
    else:
        return []
    return hEdgesShared