title: How to modify netcdf file with PyNCO ncap2?
body: <p>I'm trying to use NCO command ncap2 in python script for changing time units in the climatology NetCDF-file:</p>
  
  <pre><code>from nco import Nco
  nco = Nco()
  nco.ncap2(input='in.nc', output='out.nc', options =['-s', '\\"time@units=\\"days since 00-12-30 00:00:00\\"\\"'])
  </code></pre>
  
  <p>However, this gives me an error:</p>
  
  <blockquote>
    <p>C:\Users\test\Miniconda3\envs\download\Library\bin\ncap2 -s
    "time@units="days since 00-12-30 00:00:00"" --output=out.nc in.nc
    &lt;&lt;&lt; Inputs: out.nc b'' Traceback (most recent call last): File
    "C:\Users\test\workspace\GFSdownload\src\nc_info.py", line 13, in
     nco.ncap2(input='in.nc', output='out.nc', options =['-s',
    '\"time@units=\"days since 00-12-30 00:00:00\"\"']) File
    "C:\Users\test\Miniconda3\envs\download\lib\site-packages\nco\nco.py",
    line 342, in get raise NCOException(**retvals) nco.nco.NCOException:
    (returncode:1) b''</p>
  </blockquote>
  
  <p>While using ncap2 directly from command line works good:</p>
  
  <pre><code>ncap2 -s "time@units=\"days since 00-12-30 00:00:00\"" in.nc out.nc
  </code></pre>
  
  <p>Is there a workaround for this? I'm writing my main code in python, so I'd like to use pynco everywhere.</p>