Blockly.Python['logic_operation'] = function(block) {
  // Operations 'and', 'or'.
  var operator = (block.getFieldValue('OP') == 'AND') ? 'and' : 'or';
  var order = (operator == 'and') ? Blockly.Python.ORDER_LOGICAL_AND :
      Blockly.Python.ORDER_LOGICAL_OR;