Human: open pdf specific size. Assistant: 
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.