I am not sure whether this is a real bug or I am missing something.
circle() creates a closed BezierSpline, with the first and the last coincident points both included. When converting to Formex or Mesh this will create a degenerate element. At which level should this be corrected?

>>> from pyformex.plugins.curve import *
>>> c=circle().approx(nseg=3)
>>> c.coords
Coords([[ 1.        ,  0.        ,  0.        ],
       [-0.25952017,  0.96573782,  0.        ],
       [-0.86638832, -0.49937114,  0.        ],
       [ 1.        ,  0.        ,  0.        ]], dtype=float32)
>>> c.toFormex().coords
Coords([[[ 1.        ,  0.        ,  0.        ],
        [-0.25952017,  0.96573782,  0.        ]],

       [[-0.25952017,  0.96573782,  0.        ],
        [-0.86638832, -0.49937114,  0.        ]],

       [[-0.86638832, -0.49937114,  0.        ],
        [ 1.        ,  0.        ,  0.        ]],

       [[ 1.        ,  0.        ,  0.        ],
        [ 1.        ,  0.        ,  0.        ]]], dtype=float32)