human
does read or readline return an empty string.
assistant
Here is a Python program to does read or readline return an empty string

import sys

def read_or_readline(file):
    """
    Returns the contents of a file as a string.

    If the file is a pipe, readline() is used.

    :param file: The file to read.
    :return: The contents of the file.
    """
    if hasattr(file,'read'):
        return file.read()
    else:
        return file.readline()

# Enter the file
file = open("test.txt", "r")

# Calling the function
print((read_or_readline(file)))

#Example Output
# 1
# 2
# 3
# 4
# 5
# 6
# 7
# 8
# 9

#Remember to inspect code for bugs.