code: def src_suffixes(self, env):
          
          sdict = {}
          suffixes = self.subst_src_suffixes(env)
          for s in suffixes:
              sdict[s] = 1
          for builder in self.get_src_builders(env):
              for s in builder.src_suffixes(env):
                  if s not in sdict:
                      sdict[s] = 1
                      suffixes.append(s)
          return suffixes
docs: Returns the list of source suffixes for all src_builders of this
          Builder.
  
          This is essentially a recursive descent of the src_builder "tree."
          (This value isn't cached because there may be changes in a
          src_builder many levels deep that we can't see.)