
    Write a function that validates delivery route identifiers in the fleet management system by checking if they consist only of lowercase letters connected by underscores. The function should return true for valid route identifiers like "north_route_priority" and false for any identifiers that don't follow this format.
    

    
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 only of lowercase letters connected by underscores. The function should return true for valid route identifiers like "north_route_priority" and false for any identifiers that don't follow this format.
    

    """
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 only of lowercase letters connected by underscores. The function should return true for valid route identifiers like "north_route_priority" and false for any identifiers that don't follow this format.
    

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