# - - - T a x a T r e e . s e t R o o t def setRoot ( self, taxon ): '''Store the root taxon. '''
There are two conditions for successfully storing the root.
There must not already be a root taxon.
The candidate taxon must be at the highest rank in the hierarchy, that is, its depth must be zero.
#-- 1 -- if self.root is not None: raise ValueError ( "There is already a root taxon: " "'%s'" % self.root ) elif taxon.rank.depth != 0: raise ValueError ( "The root taxon must have rank " "%s." % self.hier ) else: self.root = taxon