be able to specify the shape of a node in the yaml
if None and name = start or end do diamond
if None or name not in start end do rounded box
if shape in node use that as the shape name
shape name could contains some special things such as style options
be able to specify the shape of a node in the yaml
if None and name = start or end do diamond if None or name not in start end do rounded box if shape in node use that as the shape name shape name could contains some special things such as style options