
    Write a function that validates whether a transaction identifier follows the bank's security protocol by checking if it consists only of lowercase letters joined with underscores. The function should return true for valid transaction identifiers (like "transfer_domestic_savings") and false for any identifiers that don't follow this pattern.
    

    
import re

def text_lowercase_underscore(text):
    """
    Write a function that validates whether a transaction identifier follows the bank's security protocol by checking if it consists only of lowercase letters joined with underscores. The function should return true for valid transaction identifiers (like "transfer_domestic_savings") and false for any identifiers that don't follow this pattern.
    

    """
import re

def text_lowercase_underscore(text):
    """
    Write a function that validates whether a transaction identifier follows the bank's security protocol by checking if it consists only of lowercase letters joined with underscores. The function should return true for valid transaction identifiers (like "transfer_domestic_savings") and false for any identifiers that don't follow this pattern.
    

    """
    patterns = '^[a-z]+_[a-z]+$'
    if re.search(patterns, text):
        return True
    else:
        return False