code: function processPartitionKeys(keys){
      var result = "(",
          j,
          len,
          keyGroup;
  
      if(typeof keys === 'string'){
          return result += keys + ")";
      }
  
      len = keys.length;
      for(j = 0; j< keys.length; j++){
          keyGroup = keys[j];
          if(keyGroup instanceof Array){
              result += "(";
              result += keyGroup.join(", ");
              result += ")";
          }else{
              result += keyGroup;
          }
          result += (j < len-1) ? ", " : "";
      }
      result += ")";
  
      return result;
  }
docs: An internal method, it processes primary partition keys into a CQL statement.
  @param  {Object} keys A string, Array or multi-dimensional Array
  @return {String}      A CQL formatted string of the partition key