text: import csv
  import sys
  import json
  
  import six
  
  
  class Example(object):
      """Defines a single training or test example.
  
      Stores each column of the example as an attribute.
      """
  
      @classmethod
      def fromJSON(cls, data, fields):
          return cls.fromdict(json.loads(data), fields)
  
      @classmethod
      def fromdict(cls, data, fields):
          ex = cls()
          for key, vals in fields.items():
              if key not in data:
                  raise ValueError("Specified key {} was not found in "
                                   "the input data".format(key))
              if vals is not None:
                  if not isinstance(vals, list):
                      vals = [vals]
                  for val in vals:
                      name, field = val
                      setattr(ex, name, [sys.intern(x) for x in field.preprocess(data[key])])
          return ex
  
      @classmethod
      def fromTSV(cls, data, fields):
          return cls.fromlist(data.split('\t'), fields)
  
      @classmethod
      def fromCSV(cls, data, fields):
          data = data.rstrip("\n")
          # If Python 2, encode to utf-8 since CSV doesn't take unicode input
          if six.PY2:
              data = data.encode('utf-8')
          # Use Python CSV module to parse the CSV line
          parsed_csv_lines = csv.reader([data])
  
          # If Python 2, decode back to unicode (the original input format).
          if six.PY2:
              for line in parsed_csv_lines:
                  parsed_csv_line = [six.text_type(col, 'utf-8') for col in line]
                  break
          else:
              parsed_csv_line = list(parsed_csv_lines)[0]
          return cls.fromlist(parsed_csv_line, fields)
  
      @classmethod
      def fromlist(cls, data, fields):
          ex = cls()
          for (name, field), val in zip(fields, data):
              if field is not None:
                  if isinstance(val, six.string_types):
                      val = val.rstrip('\n')
                  setattr(ex, name, [sys.intern(x) for x in field.preprocess(val)])
          return ex
  
      @classmethod
      def fromtree(cls, data, fields, subtrees=False):
          try:
              from nltk.tree import Tree
          except ImportError:
              print("Please install NLTK. "
                    "See the docs at http://nltk.org for more information.")
              raise
          tree = Tree.fromstring(data)
          if subtrees:
              return [cls.fromlist(
                  [' '.join(t.leaves()), t.label()], fields) for t in tree.subtrees()]
          return cls.fromlist([' '.join(tree.leaves()), tree.label()], fields)
  