old_contents: # Copyright (C) 2012 Andy Balaam and The Pepper Developers
  # Released under the MIT License.  See the file COPYING.txt for details.
  
  from libpepper.values import PepValue
  from libpepper.values import all_known
  
  class PepModification( PepValue ):
      def __init__( self, var, mod_value ):
          PepValue.__init__( self )
          self.var = var
          self.mod_value = mod_value
  
      def construction_args( self ):
          return ( self.var, self.mod_value, )
  
      def do_evaluate( self, env ):
          if self.is_known( env ):
              print "is_known"
              namespace, name, base_name = self.var.find_namespace_and_name( env )
              namespace[name].plusequals( self.mod_value.evaluate( env ) )
          return self
  
      def is_known( self, env ):
          return all_known( ( self.var, self.mod_value, ), env )
  
  
  
  
new_contents: # Copyright (C) 2012 Andy Balaam and The Pepper Developers
  # Released under the MIT License.  See the file COPYING.txt for details.
  
  from libpepper.values import PepValue
  from libpepper.values import all_known
  
  class PepModification( PepValue ):
      def __init__( self, var, mod_value ):
          PepValue.__init__( self )
          self.var = var
          self.mod_value = mod_value
  
      def construction_args( self ):
          return ( self.var, self.mod_value, )
  
      def do_evaluate( self, env ):
          if self.is_known( env ):
              namespace, name, base_name = self.var.find_namespace_and_name( env )
              namespace[name].plusequals( self.mod_value.evaluate( env ) )
          return self
  
      def is_known( self, env ):
          return all_known( ( self.var, self.mod_value, ), env )
  
  
  
  
subject: Remove debug print