class_docstr: Abstract base class from which all NPExtractor classes inherit.
  Descendant classes must implement an ``extract(text)`` method
  that returns a list of noun phrases as strings.
docstr: Return a list of noun phrases (strings) for a body of text.
docstr_tok: ["Return","a","list","of","noun","phrases","(","strings",")","for","a","body","of","text","."]
code: def extract(self, text):
      """Return a list of noun phrases (strings) for a body of text."""
      return
  
imports: from __future__ import absolute_import
  from abc import ABCMeta, abstractmethod
  import nltk
  from textblob.compat import with_metaclass
label_desc: Use image node_id 1 for calling the BaseNPExtractor obj's underlying member method code with example usage: obj.extract(text) without return types