
    Write a function that validates delivery route identifiers in a fleet management system by checking if the input string consists of lowercase letters connected by underscores. The function should return true for valid route identifiers (like "north_route_express") and false for invalid ones, ensuring consistent naming conventions across the transportation network.
    

    
import re

def text_lowercase_underscore(text):
    """
    Write a function that validates delivery route identifiers in a fleet management system by checking if the input string consists of lowercase letters connected by underscores. The function should return true for valid route identifiers (like "north_route_express") and false for invalid ones, ensuring consistent naming conventions across the transportation network.
    

    """
import re

def text_lowercase_underscore(text):
    """
    Write a function that validates delivery route identifiers in a fleet management system by checking if the input string consists of lowercase letters connected by underscores. The function should return true for valid route identifiers (like "north_route_express") and false for invalid ones, ensuring consistent naming conventions across the transportation network.
    

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