code: def plot_map(raw_data, variable, limits, filename):
      fig, ax = plt.subplots(1)
      lower, upper = limits
      ax.set_title("Map for {}".format(variable))
      im = ax.imshow(
          raw_data.T,
          origin="lower",
          clim=(lower, upper),
          cmap="gray",
          interpolation="nearest",
      )
      fig.colorbar(im)
      fig.savefig(filename)
  
imports: import matplotlib.pyplot
  from dipy.reconst.ivim import IvimModel
  from dipy.core.gradients import gradient_table
  from dipy.data import get_fnames
  from dipy.io.gradients import read_bvals_bvecs
  from dipy.io.image import load_nifti_data
label_desc: Use image node_id 1 for calling a global function with example usage: plot_map(raw_data, variable, limits, filename) without return types