title: 'DataFrame' object has no attribute 'isna'
body: <p>I have adapted one machine learning code for one my project.The code that worked fine on my laptop ,now makes problems on my desktop.I am checking all data frame columns for missing values.</p>
  
  <pre><code>  File "g100.py", line 11, in &lt;module&gt;
      print(dfs.columns[dfs.isna().any()].tolist()) 
  AttributeError: 'DataFrame' object has no attribute 'isna'
  </code></pre>
  
  <p>My installed panda versions and dependencies</p>
  
  <pre><code>d.show_versions(as_json=False)
  
  INSTALLED VERSIONS
  ------------------
  commit: None
  python: 3.6.3.final.0
  python-bits: 64
  OS: Linux
  OS-release: 4.13.0-37-generic
  machine: x86_64
  processor: x86_64
  byteorder: little
  LC_ALL: None
  LANG: en_US.UTF-8
  LOCALE: en_US.UTF-8
  
  pandas: 0.20.3
  pytest: 3.4.2
  pip: 9.0.3
  setuptools: 38.5.1
  Cython: None
  numpy: 1.11.3
  scipy: 0.19.0
  xarray: None
  IPython: 6.2.1
  sphinx: None
  patsy: 0.5.0
  dateutil: 2.6.0
  pytz: 2017.3
  blosc: None
  bottleneck: None
  tables: 3.4.2
  numexpr: 2.6.4
  feather: None
  matplotlib: 2.1.2
  openpyxl: None
  xlrd: 1.1.0
  xlwt: None
  xlsxwriter: None
  lxml: None
  bs4: 4.6.0
  html5lib: 0.9999999
  sqlalchemy: 1.1.9
  pymysql: None
  psycopg2: 2.7.4 (dt dec pq3 ext lo64)
  jinja2: 2.10
  s3fs: None
  pandas_gbq: None
  pandas_datareader: 0.6.0
  </code></pre>
  
  <p>I can find an explanation why isna gives me an AttributeError.</p>