code: def page_file(fname, start=0, pager_cmd=None):
      """Page a file, using an optional pager command and starting line."""
  
      pager_cmd = get_pager_cmd(pager_cmd)
      pager_cmd += " " + get_pager_start(pager_cmd, start)
  
      try:
          if os.environ["TERM"] in ["emacs", "dumb"]:
              raise EnvironmentError
          system(pager_cmd + " " + fname)
      except:
          try:
              if start > 0:
                  start -= 1
              page(open(fname, encoding="utf-8").read(), start)
          except:
              print("Unable to show file", repr(fname))
  
imports: import os
  import io
  import re
  import sys
  import tempfile
  import subprocess
  from io import UnsupportedOperation
  from pathlib import Path
  from IPython import get_ipython
  from IPython.display import display
  from IPython.core.error import TryNext
  from IPython.utils.data import chop
  from IPython.utils.process import system
  from IPython.utils.terminal import get_terminal_size
  from IPython.utils import py3compat
label_desc: Use image node_id 7 for calling a global function with example usage: page_file(fname, start, pager_cmd) without return types