
    Write a function that validates delivery route identifiers in the fleet management system by checking if they consist of lowercase segments joined by underscores. The function should return true for valid route identifiers like "north_route_priority" and false for invalid formats like "North-Route" or "express.delivery", ensuring consistent route naming conventions across the delivery optimization platform.
    

    
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 segments joined by underscores. The function should return true for valid route identifiers like "north_route_priority" and false for invalid formats like "North-Route" or "express.delivery", ensuring consistent route naming conventions across the delivery optimization platform.
    

    """
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 segments joined by underscores. The function should return true for valid route identifiers like "north_route_priority" and false for invalid formats like "North-Route" or "express.delivery", ensuring consistent route naming conventions across the delivery optimization platform.
    

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