code: def init_file(self, filename, time_units="seconds since 1970-01-01T00:00"):
          
          if os.access(filename, os.R_OK):
              out_data = Dataset(filename, "r+")
          else:
              out_data = Dataset(filename, "w")
              if len(self.data.shape) == 2:
                  for d, dim in enumerate(["y", "x"]):
                      out_data.createDimension(dim, self.data.shape[d])
              else:
                  for d, dim in enumerate(["y", "x"]):
                      out_data.createDimension(dim, self.data.shape[d+1])
              out_data.createDimension("time", len(self.times))
              time_var = out_data.createVariable("time", "i8", ("time",))
              time_var[:] = date2num(self.times.to_pydatetime(), time_units)
              time_var.units = time_units
              out_data.Conventions = "CF-1.6"
          return out_data
docs: Initializes netCDF file for writing
  
          Args:
              filename: Name of the netCDF file
              time_units: Units for the time variable in format "<time> since <date string>"
          Returns:
              Dataset object