function writeFlowMapping(state, level, object) {
  var _result       = '',
      _tag          = state.tag,
      objectKeyList = Object.keys(object),
      index,
      length,
      objectKey,
      objectValue,
      pairBuffer;

  for (index = 0, length = objectKeyList.length; index < length; index += 1) {

    pairBuffer = '';
    if (index !== 0) pairBuffer += ', ';

    if (state.condenseFlow) pairBuffer += '"';

    objectKey = objectKeyList[index];
    objectValue = object[objectKey];

    if (!writeNode(state, level, objectKey, false, false)) {
      continue; // Skip this pair because of invalid key;
    }

    if (state.dump.length > 1024) pairBuffer += '? ';

    pairBuffer += state.dump + (state.condenseFlow ? '"' : '') + ':' + (state.condenseFlow ? '' : ' ');

    if (!writeNode(state, level, objectValue, false, false)) {
      continue; // Skip this pair because of invalid value.
    }

    pairBuffer += state.dump;

    // Both key and value are valid.
    _result += pairBuffer;
  }

  state.tag = _tag;
  state.dump = '{' + _result + '}';
}
Internal method that keeps a track of which error we have already added, to avoid circular recursion

@private
@param {Error} err
@param {Set<Error>} seen
@param {boolean} [skip]
@returns {string}