code: function _makeQuery(conditions, fields) {
    // build up 'Where' string
    var query = fields.reduce(function(condition, field) {
      var addition = '';
      var val = conditions[field];
      var isNumber = typeof val === 'number';
      if (val) {
        addition += field;
        if (isNumber) {
          addition += '=';
        } else {
          addition += ' like \'';
        }
  
        addition += val;
  
        if (!isNumber) {
          addition += '\'';
        }
  
        addition += ' and ';
      }
      return condition + addition;
    }, 'Where ');
  
    // remove final 'and'
    query = query.replace(/ and $/, '');
    return new nodeGoogleDfp.Statement(query);
  }
docs: Converts an object of conditions and possible query fields into a
  node-google-dfp statement to query DFP.
  
  @param  {Object} conditions An object of the properties you'd like to query
  and the values you'd like them to contain.
  @param  {Array} fields      All the fields it is possible to query, as
  detailed in the DFP api.
  @return {Object}            node-google-dfp statement.