code: public CFMetaData getCFMetaData(String keyspaceName, String cfName)
      {
          assert keyspaceName != null;
          KSMetaData ksm = keyspaces.get(keyspaceName);
          return (ksm == null) ? null : ksm.cfMetaData().get(cfName);
      }
docs: Given a keyspace name & column family name, get the column family
  meta data. If the keyspace name or column family name is not valid
  this function returns null.
  
  @param keyspaceName The keyspace name
  @param cfName The ColumnFamily name
  
  @return ColumnFamily Metadata object or null if it wasn't found