class_docstr: Patch pygac.
docstr: Patch pygac imports.
code: def setUp(self):
      """Patch pygac imports."""
      self.pygac = mock.MagicMock()
      self.fhs = mock.MagicMock()
      modules = {
          "pygac": self.pygac,
          "pygac.gac_klm": self.pygac.gac_klm,
          "pygac.gac_pod": self.pygac.gac_pod,
          "pygac.lac_klm": self.pygac.lac_klm,
          "pygac.lac_pod": self.pygac.lac_pod,
          "pygac.utils": self.pygac.utils,
          "pygac.calibration": self.pygac.calibration,
      }
  
      self.module_patcher = mock.patch.dict("sys.modules", modules)
      self.module_patcher.start()
  
imports: from datetime import datetime
  from unittest import TestCase, mock
  import dask.array
  import numpy
  import pytest
  import xarray
label_desc: Use image node_id 1 for calling the PygacPatcher obj's underlying member method code with example usage: obj.setUp() without return types