
    Write a function that validates if a transaction identifier follows the bank's standardized format by checking if it consists only of lowercase letter sequences connected by underscores. The function should return true if the transaction identifier matches this required pattern, and false if it contains any deviation from this format.
    

    
import re

def text_lowercase_underscore(text):
    """
    Write a function that validates if a transaction identifier follows the bank's standardized format by checking if it consists only of lowercase letter sequences connected by underscores. The function should return true if the transaction identifier matches this required pattern, and false if it contains any deviation from this format.
    

    """
import re

def text_lowercase_underscore(text):
    """
    Write a function that validates if a transaction identifier follows the bank's standardized format by checking if it consists only of lowercase letter sequences connected by underscores. The function should return true if the transaction identifier matches this required pattern, and false if it contains any deviation from this format.
    

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