function parseConversion(state) {
    var node, operators, name, fn, params;
    node = parseRange(state);
    operators = {
      'to': 'to',
      'in': 'to' // alias of 'to'

    };

    while (operators.hasOwnProperty(state.token)) {
      name = state.token;
      fn = operators[name];
      getTokenSkipNewline(state);

      if (name === 'in' && state.token === '') {
        // end of expression -> this is the unit 'in' ('inch')
        node = new OperatorNode('*', 'multiply', [node, new SymbolNode('in')], true);
      } else {
        // operator 'a to b' or 'a in b'
        params = [node, parseRange(state)];
        node = new OperatorNode(name, fn, params);
      }
    }

    return node;
  }
conversion operators 'to' and 'in'
@return {Node} node
@private