old_contents: import numpy as np
  import xray
  
  mp = 'Marshall and Plumb'
  
  constants = xray.Dataset()
  
  constants['g'] = xray.DataArray(
      9.81,
      attrs={'name' : "Earth's surface gravity",
             'units' : 'm s^-2',
             'ref' : mp
            })
  
  constants['R'] = xray.DataArray(
      6.37e6,
      attrs={'name' : "Earth's mean radius",
             'units' : 'm',
             'ref' : mp
             })
  
new_contents: import numpy as np
  import xray
  
  mp = ('Atmosphere, Ocean, and Climate Dynamics: An Introductory Text,'
      'by John Marshall and R. Alan Plumb, 2008')
  
  constants = xray.Dataset()
  
  constants['g'] = xray.DataArray(
      9.81,
      attrs={'name' : "Earth's surface gravity",
             'units' : 'm s^-2',
             'ref' : mp
            })
  
  constants['R'] = xray.DataArray(
      6.37e6,
      attrs={'name' : "Earth's mean radius",
             'units' : 'm',
             'ref' : mp
            })
  
  
  constants['STP_T'] = xray.DataArray(
      273,
      attrs={'name' : 'Temperature at STP,
             'units' : 'K',
             'ref' : mp
            })
  
  
  constants['STP_p'] = xray.DataArray(
      101325,
      attrs={'name' : 'Pressure at STP,
             'units' : 'Pa',
             'ref' : mp
            })
  
  constants['Omega'] = xray.DataArray(
      7.27e-5,
      attrs={'name' : "Earth's rotation rate",
             'units' : 's^-1',
             'ref' : mp
            })
  
  constants['Cp'] = xray.DataArray(
      1005,
      attrs={'name' : 'Dry air specific heat at constant pressure, at STP',
             'units' : 'J kg^-1 K^-1',
             'ref' : mp
            })
  
  constants['Cv'] = xray.DataArray(
      718,
      attrs={'name' : 'Dry air specific heat at constant volume, at STP',
             'units' : 'J kg^-1 K^-1',
             'ref' : mp
            })
  
subject: Update vars.py