Human: how to replace multiple substring from a string in. Assistant: 
Here is a Python function to replace multiple substrings from a string

import random

def replace_substring(string, substring, replacement):
    """Replace multiple substring from a string in."""
    return string.replace(substring, replacement)

# Enter the string
string = "This is a string"

# Enter the substring
substring = "is"

# Enter the replacement
replacement = "are"

# Calling the function
print((replace_substring(string, substring, replacement)))

#Example Output
# Thare are a string

#Remember to inspect code for bugs.