code: def test_multipage_pagecount():
      with PdfPages(io.BytesIO()) as pdf:
          assert pdf.get_pagecount() == 0
          fig, ax = plt.subplots()
          ax.plot([1, 2, 3])
          fig.savefig(pdf, format="pdf")
          assert pdf.get_pagecount() == 1
          pdf.savefig()
          assert pdf.get_pagecount() == 2
  
imports: import datetime
  import decimal
  import io
  import os
  from pathlib import Path
  import numpy
  import pytest
  import matplotlib
  from matplotlib import pyplot, rcParams, font_manager
  from matplotlib.cbook import _get_data_path
  from matplotlib.ft2font import FT2Font
  from matplotlib.font_manager import findfont, FontProperties
  from matplotlib.backends._backend_pdf_ps import get_glyphs_subset
  from matplotlib.backends.backend_pdf import PdfPages
  from matplotlib.patches import Rectangle
  from matplotlib.testing.decorators import check_figures_equal, image_comparison
  from matplotlib.testing._markers import needs_usetex
label_desc: Use image node_id 3 for calling a global function with example usage: test_multipage_pagecount() without return types