
    Write a function that validates delivery route identifiers in the fleet management system by checking if they consist of lowercase letters connected by underscores. The function should return true for valid route identifiers that follow this format, and false for any identifiers that deviate from this naming convention.
    

    
import re

def text_lowercase_underscore(text):
    """
    Write a function that validates delivery route identifiers in the fleet management system by checking if they consist of lowercase letters connected by underscores. The function should return true for valid route identifiers that follow this format, and false for any identifiers that deviate from this naming convention.
    

    """
import re

def text_lowercase_underscore(text):
    """
    Write a function that validates delivery route identifiers in the fleet management system by checking if they consist of lowercase letters connected by underscores. The function should return true for valid route identifiers that follow this format, and false for any identifiers that deviate from this naming convention.
    

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