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Python function to separate upper letter with underscore.
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Here is a Python function to separate upper letter with underscore

import pandas as pd

def separate_upper_letter_with_underscore(s):
    """Separate upper letter with underscore."""
    return s.replace("_", " ").upper()

# Enter the string
s = "This is a string with upper letter and underscore"

# Calling the function
print(s)
print((separate_upper_letter_with_underscore(s)))

#Example Output
# This is a string with upper letter and underscore
# THIS IS A STRING WITH UPPER LETTER AND UNDERSCORE

#Remember to inspect code for bugs.