<human>:  What is a good Python function to open pdf specific size.
<bot>: Here is a Python function to open pdf specific size

import os

def open_pdf(filename, size=None):
  """
  Open a PDF file.
  """
  if size is None:
    size = (1000, 1000)
  return open(filename, 'rb')

# Enter the filename
filename = 'test.pdf'

# Calling the function
print((open_pdf(filename)))

#Example Output
# <_io.BufferedReader name='test.pdf'>

#Remember to inspect code for bugs.